CINXE.COM

<!doctype html><html lang="en-US" prefix="og: https://ogp.me/ns#"><head><meta charSet="utf-8"/><meta name="viewport" content="width=device-width,initial-scale=1"/><link rel="icon" href="https://developer.mozilla.org/favicon-48x48.bc390275e955dacb2e65.png"/><link rel="apple-touch-icon" href="https://developer.mozilla.org/apple-touch-icon.528534bba673c38049c2.png"/><meta name="theme-color" content="#ffffff"/><link rel="manifest" href="https://developer.mozilla.org/manifest.f42880861b394dd4dc9b.json"/><link rel="search" type="application/opensearchdescription+xml" href="/opensearch.xml" title="MDN Web Docs"/><title>RequestInit - Web APIs | MDN</title><link rel="alternate" title="RequestInit" href="https://developer.mozilla.org/de/docs/Web/API/RequestInit" hrefLang="de"/><link rel="alternate" title="RequestInit" href="https://developer.mozilla.org/ja/docs/Web/API/RequestInit" hrefLang="ja"/><link rel="alternate" title="RequestInit" href="https://developer.mozilla.org/en-US/docs/Web/API/RequestInit" hrefLang="en"/><link rel="preload" as="font" type="font/woff2" href="/static/media/Inter.var.c2fe3cb2b7c746f7966a.woff2" crossorigin=""/><link rel="alternate" type="application/rss+xml" title="MDN Blog RSS Feed" href="https://developer.mozilla.org/en-US/blog/rss.xml" hrefLang="en"/><meta name="description" content="Learn about the RequestInit interface, including its properties, code examples and specifications."/><meta property="og:url" content="https://developer.mozilla.org/en-US/docs/Web/API/RequestInit"/><meta property="og:title" content="RequestInit - Web APIs | MDN"/><meta property="og:type" content="website"/><meta property="og:locale" content="en_US"/><meta property="og:description" content="The RequestInit dictionary of the Fetch API represents the set of options that can be used to configure a Fetch request."/><meta property="og:image" content="https://developer.mozilla.org/mdn-social-share.d893525a4fb5fb1f67a2.png"/><meta property="og:image:type" content="image/png"/><meta property="og:image:height" content="1080"/><meta property="og:image:width" content="1920"/><meta property="og:image:alt" content="The MDN Web Docs logo, featuring a blue accent color, displayed on a solid black background."/><meta property="og:site_name" content="MDN Web Docs"/><meta name="twitter:card" content="summary_large_image"/><meta name="twitter:creator" content="MozDevNet"/><link rel="canonical" href="https://developer.mozilla.org/en-US/docs/Web/API/RequestInit"/><style media="print">.article-actions-container,.document-toc-container,.language-menu,.main-menu-toggle,.on-github,.page-footer,.place,.sidebar,.top-banner,.top-navigation-main,ul.prev-next{display:none!important}.main-page-content,.main-page-content pre{padding:2px}.main-page-content pre{border-left-width:2px}</style><script src="/static/js/gtag.js" defer=""></script><script defer="" src="/static/js/main.5e889624.js"></script><link href="/static/css/main.26c64ea7.css" rel="stylesheet"/></head><body><script>if(document.body.addEventListener("load",(t=>{t.target.classList.contains("interactive")&&t.target.setAttribute("data-readystate","complete")}),{capture:!0}),window&&document.documentElement){const t={light:"#ffffff",dark:"#1b1b1b"};try{const e=window.localStorage.getItem("theme");e&&(document.documentElement.className=e,document.documentElement.style.backgroundColor=t[e]);const o=window.localStorage.getItem("nop");o&&(document.documentElement.dataset.nop=o)}catch(t){console.warn("Unable to read theme from localStorage",t)}}</script><div id="root"><ul id="nav-access" class="a11y-nav"><li><a id="skip-main" href="#content">Skip to main content</a></li><li><a id="skip-search" href="#top-nav-search-input">Skip to search</a></li><li><a id="skip-select-language" href="#languages-switcher-button">Skip to select language</a></li></ul><div class="page-wrapper category-api document-page"><div class="top-banner loading"><section class="place top container"></section></div><div class="sticky-header-container"><header class="top-navigation "><div class="container "><div class="top-navigation-wrap"><a href="/en-US/" class="logo" aria-label="MDN homepage"><svg id="mdn-docs-logo" xmlns="http://www.w3.org/2000/svg" x="0" y="0" viewBox="0 0 694.9 104.4" style="enable-background:new 0 0 694.9 104.4" xml:space="preserve" role="img"><title>MDN Web Docs</title><path d="M40.3 0 11.7 92.1H0L28.5 0h11.8zm10.4 0v92.1H40.3V0h10.4zM91 0 62.5 92.1H50.8L79.3 0H91zm10.4 0v92.1H91V0h10.4z" class="logo-m"></path><path d="M627.9 95.6h67v8.8h-67v-8.8z" class="logo-_"></path><path d="M367 42h-4l-10.7 30.8h-5.5l-10.8-26h-.4l-10.5 26h-5.2L308.7 42h-3.8v-5.6H323V42h-6.5l6.8 20.4h.4l10.3-26h4.7l11.2 26h.5l5.7-20.3h-6.2v-5.6H367V42zm34.9 20c-.4 3.2-2 5.9-4.7 8.2-2.8 2.3-6.5 3.4-11.3 3.4-5.4 0-9.7-1.6-13.1-4.7-3.3-3.2-5-7.7-5-13.7 0-5.7 1.6-10.3 4.7-14s7.4-5.5 12.9-5.5c5.1 0 9.1 1.6 11.9 4.7s4.3 6.9 4.3 11.3c0 1.5-.2 3-.5 4.7h-25.6c.3 7.7 4 11.6 10.9 11.6 2.9 0 5.1-.7 6.5-2 1.5-1.4 2.5-3 3-4.9l6 .9zM394 51.3c.2-2.4-.4-4.7-1.8-6.9s-3.8-3.3-7-3.3c-3.1 0-5.3 1-6.9 3-1.5 2-2.5 4.4-2.8 7.2H394zm51 2.4c0 5-1.3 9.5-4 13.7s-6.9 6.2-12.7 6.2c-6 0-10.3-2.2-12.7-6.7-.1.4-.2 1.4-.4 2.9s-.3 2.5-.4 2.9h-7.3c.3-1.7.6-3.5.8-5.3.3-1.8.4-3.7.4-5.5V22.3h-6v-5.6H416v27c1.1-2.2 2.7-4.1 4.7-5.7 2-1.6 4.8-2.4 8.4-2.4 4.6 0 8.4 1.6 11.4 4.7 3 3.2 4.5 7.6 4.5 13.4zm-7.7.6c0-4.2-1-7.4-3-9.5-2-2.2-4.4-3.3-7.4-3.3-3.4 0-6 1.2-8 3.7-1.9 2.4-2.9 5-3 7.7V57c0 3 1 5.6 3 7.7s4.5 3.1 7.6 3.1c3.6 0 6.3-1.3 8.1-3.9 1.8-2.7 2.7-5.9 2.7-9.6zm69.2 18.5h-13.2v-7.2c-1.2 2.2-2.8 4.1-4.9 5.6-2.1 1.6-4.8 2.4-8.3 2.4-4.8 0-8.7-1.6-11.6-4.9-2.9-3.2-4.3-7.7-4.3-13.3 0-5 1.3-9.6 4-13.7 2.6-4.1 6.9-6.2 12.8-6.2 5.7 0 9.8 2.2 12.3 6.5V22.3h-8.6v-5.6h15.8v50.6h6v5.5zM493.2 56v-4.4c-.1-3-1.2-5.5-3.2-7.3s-4.4-2.8-7.2-2.8c-3.6 0-6.3 1.3-8.2 3.9-1.9 2.6-2.8 5.8-2.8 9.6 0 4.1 1 7.3 3 9.5s4.5 3.3 7.4 3.3c3.2 0 5.8-1.3 7.8-3.8 2.1-2.6 3.1-5.3 3.2-8zm53.1-1.4c0 5.6-1.8 10.2-5.3 13.7s-8.2 5.3-13.9 5.3-10.1-1.7-13.4-5.1c-3.3-3.4-5-7.9-5-13.5 0-5.3 1.6-9.9 4.7-13.7 3.2-3.8 7.9-5.7 14.2-5.7s11 1.9 14.1 5.7c3 3.7 4.6 8.1 4.6 13.3zm-7.7-.2c0-4-1-7.2-3-9.5s-4.8-3.5-8.2-3.5c-3.6 0-6.4 1.2-8.3 3.7s-2.9 5.6-2.9 9.5c0 3.7.9 6.8 2.8 9.4 1.9 2.6 4.6 3.9 8.3 3.9 3.6 0 6.4-1.3 8.4-3.8 1.9-2.6 2.9-5.8 2.9-9.7zm45 5.8c-.4 3.2-1.9 6.3-4.4 9.1-2.5 2.9-6.4 4.3-11.8 4.3-5.2 0-9.4-1.6-12.6-4.8-3.2-3.2-4.8-7.7-4.8-13.7 0-5.5 1.6-10.1 4.7-13.9 3.2-3.8 7.6-5.7 13.2-5.7 2.3 0 4.6.3 6.7.8 2.2.5 4.2 1.5 6.2 2.9l1.5 9.5-5.9.7-1.3-6.1c-2.1-1.2-4.5-1.8-7.2-1.8-3.5 0-6.1 1.2-7.7 3.7-1.7 2.5-2.5 5.7-2.5 9.6 0 4.1.9 7.3 2.7 9.5 1.8 2.3 4.4 3.4 7.8 3.4 5.2 0 8.2-2.9 9.2-8.8l6.2 1.3zm34.7 1.9c0 3.6-1.5 6.5-4.6 8.5s-7 3-11.7 3c-5.7 0-10.6-1.2-14.6-3.6l1.2-8.8 5.7.6-.2 4.7c1.1.5 2.3.9 3.6 1.1s2.6.3 3.9.3c2.4 0 4.5-.4 6.5-1.3 1.9-.9 2.9-2.2 2.9-4.1 0-1.8-.8-3.1-2.3-3.8s-3.5-1.3-5.8-1.7-4.6-.9-6.9-1.4c-2.3-.6-4.2-1.6-5.7-2.9-1.6-1.4-2.3-3.5-2.3-6.3 0-4.1 1.5-6.9 4.6-8.5s6.4-2.4 9.9-2.4c2.6 0 5 .3 7.2.9 2.2.6 4.3 1.4 6.1 2.4l.8 8.8-5.8.7-.8-5.7c-2.3-1-4.7-1.6-7.2-1.6-2.1 0-3.7.4-5.1 1.1-1.3.8-2 2-2 3.8 0 1.7.8 2.9 2.3 3.6 1.5.7 3.4 1.2 5.7 1.6 2.2.4 4.5.8 6.7 1.4 2.2.6 4.1 1.6 5.7 3 1.4 1.6 2.2 3.7 2.2 6.6zM197.6 73.2h-17.1v-5.5h3.8V51.9c0-3.7-.7-6.3-2.1-7.9-1.4-1.6-3.3-2.3-5.7-2.3-3.2 0-5.6 1.1-7.2 3.4s-2.4 4.6-2.5 6.9v15.6h6v5.5h-17.1v-5.5h3.8V51.9c0-3.8-.7-6.4-2.1-7.9-1.4-1.5-3.3-2.3-5.6-2.3-3.2 0-5.5 1.1-7.2 3.3-1.6 2.2-2.4 4.5-2.5 6.9v15.8h6.9v5.5h-20.2v-5.5h6V42.4h-6.1v-5.6h13.4v6.4c1.2-2.1 2.7-3.8 4.7-5.2 2-1.3 4.4-2 7.3-2s5.3.7 7.5 2.1c2.2 1.4 3.7 3.5 4.5 6.4 1.1-2.5 2.7-4.5 4.9-6.1s4.8-2.4 7.9-2.4c3.5 0 6.5 1.1 8.9 3.3s3.7 5.6 3.7 10.2v18.2h6.1v5.5zm42.5 0h-13.2V66c-1.2 2.2-2.8 4.1-4.9 5.6-2.1 1.6-4.8 2.4-8.3 2.4-4.8 0-8.7-1.6-11.6-4.9-2.9-3.2-4.3-7.7-4.3-13.3 0-5 1.3-9.6 4-13.7 2.6-4.1 6.9-6.2 12.8-6.2s9.8 2.2 12.3 6.5V22.7h-8.6v-5.6h15.8v50.6h6v5.5zm-13.3-16.8V52c-.1-3-1.2-5.5-3.2-7.3s-4.4-2.8-7.2-2.8c-3.6 0-6.3 1.3-8.2 3.9-1.9 2.6-2.8 5.8-2.8 9.6 0 4.1 1 7.3 3 9.5s4.5 3.3 7.4 3.3c3.2 0 5.8-1.3 7.8-3.8 2.1-2.6 3.1-5.3 3.2-8zm61.5 16.8H269v-5.5h6V51.9c0-3.7-.7-6.3-2.2-7.9-1.4-1.6-3.4-2.3-5.7-2.3-3.1 0-5.6 1-7.4 3s-2.8 4.4-2.9 7v15.9h6v5.5h-19.3v-5.5h6V42.4h-6.2v-5.6h13.6V43c2.6-4.6 6.8-6.9 12.7-6.9 3.6 0 6.7 1.1 9.2 3.3s3.7 5.6 3.7 10.2v18.2h6v5.4h-.2z" class="logo-text"></path></svg></a><button title="Open main menu" type="button" class="button action has-icon main-menu-toggle" aria-haspopup="menu" aria-label="Open main menu" aria-expanded="false"><span class="button-wrap"><span class="icon icon-menu "></span><span class="visually-hidden">Open main menu</span></span></button></div><div class="top-navigation-main"><nav class="main-nav" aria-label="Main menu"><ul class="main-menu nojs"><li class="top-level-entry-container active"><button type="button" id="references-button" class="top-level-entry menu-toggle" aria-controls="references-menu" aria-expanded="false">References</button><a href="/en-US/docs/Web" class="top-level-entry">References</a><ul id="references-menu" class="submenu references hidden inline-submenu-lg" aria-labelledby="references-button"><li class="apis-link-container mobile-only "><a href="/en-US/docs/Web" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Overview / Web Technology</div><p class="submenu-item-description">Web technology reference for developers</p></div></a></li><li class="html-link-container "><a href="/en-US/docs/Web/HTML" class="submenu-item "><div class="submenu-icon html"></div><div class="submenu-content-container"><div class="submenu-item-heading">HTML</div><p class="submenu-item-description">Structure of content on the web</p></div></a></li><li class="css-link-container "><a href="/en-US/docs/Web/CSS" class="submenu-item "><div class="submenu-icon css"></div><div class="submenu-content-container"><div class="submenu-item-heading">CSS</div><p class="submenu-item-description">Code used to describe document style</p></div></a></li><li class="javascript-link-container "><a href="/en-US/docs/Web/JavaScript" class="submenu-item "><div class="submenu-icon javascript"></div><div class="submenu-content-container"><div class="submenu-item-heading">JavaScript</div><p class="submenu-item-description">General-purpose scripting language</p></div></a></li><li class="http-link-container "><a href="/en-US/docs/Web/HTTP" class="submenu-item "><div class="submenu-icon http"></div><div class="submenu-content-container"><div class="submenu-item-heading">HTTP</div><p class="submenu-item-description">Protocol for transmitting web resources</p></div></a></li><li class="apis-link-container "><a href="/en-US/docs/Web/API" class="submenu-item "><div class="submenu-icon apis"></div><div class="submenu-content-container"><div class="submenu-item-heading">Web APIs</div><p class="submenu-item-description">Interfaces for building web applications</p></div></a></li><li class="apis-link-container "><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Web Extensions</div><p class="submenu-item-description">Developing extensions for web browsers</p></div></a></li><li class="apis-link-container desktop-only "><a href="/en-US/docs/Web" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Web Technology</div><p class="submenu-item-description">Web technology reference for developers</p></div></a></li></ul></li><li class="top-level-entry-container "><button type="button" id="guides-button" class="top-level-entry menu-toggle" aria-controls="guides-menu" aria-expanded="false">Guides</button><a href="/en-US/docs/Learn" class="top-level-entry">Guides</a><ul id="guides-menu" class="submenu guides hidden inline-submenu-lg" aria-labelledby="guides-button"><li class="apis-link-container mobile-only "><a href="/en-US/docs/Learn" class="submenu-item "><div class="submenu-icon learn"></div><div class="submenu-content-container"><div class="submenu-item-heading">Overview / MDN Learning Area</div><p class="submenu-item-description">Learn web development</p></div></a></li><li class="apis-link-container desktop-only "><a href="/en-US/docs/Learn" class="submenu-item "><div class="submenu-icon learn"></div><div class="submenu-content-container"><div class="submenu-item-heading">MDN Learning Area</div><p class="submenu-item-description">Learn web development</p></div></a></li><li class="html-link-container "><a href="/en-US/docs/Learn/HTML" class="submenu-item "><div class="submenu-icon html"></div><div class="submenu-content-container"><div class="submenu-item-heading">HTML</div><p class="submenu-item-description">Learn to structure web content with HTML</p></div></a></li><li class="css-link-container "><a href="/en-US/docs/Learn/CSS" class="submenu-item "><div class="submenu-icon css"></div><div class="submenu-content-container"><div class="submenu-item-heading">CSS</div><p class="submenu-item-description">Learn to style content using CSS</p></div></a></li><li class="javascript-link-container "><a href="/en-US/docs/Learn/JavaScript" class="submenu-item "><div class="submenu-icon javascript"></div><div class="submenu-content-container"><div class="submenu-item-heading">JavaScript</div><p class="submenu-item-description">Learn to run scripts in the browser</p></div></a></li><li class=" "><a href="/en-US/docs/Web/Accessibility" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Accessibility</div><p class="submenu-item-description">Learn to make the web accessible to all</p></div></a></li></ul></li><li class="top-level-entry-container "><button type="button" id="mdn-plus-button" class="top-level-entry menu-toggle" aria-controls="mdn-plus-menu" aria-expanded="false">Plus</button><a href="/en-US/plus" class="top-level-entry">Plus</a><ul id="mdn-plus-menu" class="submenu mdn-plus hidden inline-submenu-lg" aria-labelledby="mdn-plus-button"><li class=" "><a href="/en-US/plus" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Overview</div><p class="submenu-item-description">A customized MDN experience</p></div></a></li><li class=" "><a href="/en-US/plus/ai-help" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">AI Help</div><p class="submenu-item-description">Get real-time assistance and support</p></div></a></li><li class=" "><a href="/en-US/plus/updates" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Updates</div><p class="submenu-item-description">All browser compatibility updates at a glance</p></div></a></li><li class=" "><a href="/en-US/plus/docs/features/overview" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Documentation</div><p class="submenu-item-description">Learn how to use MDN Plus</p></div></a></li><li class=" "><a href="/en-US/plus/docs/faq" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">FAQ</div><p class="submenu-item-description">Frequently asked questions about MDN Plus</p></div></a></li></ul></li><li class="top-level-entry-container "><a class="top-level-entry menu-link" href="/en-US/curriculum/">Curriculum <sup class="new">New</sup></a></li><li class="top-level-entry-container "><a class="top-level-entry menu-link" href="/en-US/blog/">Blog</a></li><li class="top-level-entry-container "><button type="button" id="tools-button" class="top-level-entry menu-toggle" aria-controls="tools-menu" aria-expanded="false">Tools</button><ul id="tools-menu" class="submenu tools hidden inline-submenu-lg" aria-labelledby="tools-button"><li class=" "><a href="/en-US/play" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">Playground</div><p class="submenu-item-description">Write, test and share your code</p></div></a></li><li class=" "><a href="/en-US/observatory" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">HTTP Observatory</div><p class="submenu-item-description">Scan a website for free</p></div></a></li><li class=" "><a href="/en-US/plus/ai-help" class="submenu-item "><div class="submenu-icon"></div><div class="submenu-content-container"><div class="submenu-item-heading">AI Help</div><p class="submenu-item-description">Get real-time assistance and support</p></div></a></li></ul></li></ul></nav><div class="header-search"><form action="/en-US/search" class="search-form search-widget" id="top-nav-search-form" role="search"><label id="top-nav-search-label" for="top-nav-search-input" class="visually-hidden">Search MDN</label><input aria-activedescendant="" aria-autocomplete="list" aria-controls="top-nav-search-menu" aria-expanded="false" aria-labelledby="top-nav-search-label" autoComplete="off" id="top-nav-search-input" role="combobox" type="search" class="search-input-field" name="q" placeholder=" " required="" value=""/><button type="button" class="button action has-icon clear-search-button"><span class="button-wrap"><span class="icon icon-cancel "></span><span class="visually-hidden">Clear search input</span></span></button><button type="submit" class="button action has-icon search-button"><span class="button-wrap"><span class="icon icon-search "></span><span class="visually-hidden">Search</span></span></button><div id="top-nav-search-menu" role="listbox" aria-labelledby="top-nav-search-label"></div></form></div><div class="theme-switcher-menu"><button type="button" class="button action has-icon theme-switcher-menu small" aria-haspopup="menu"><span class="button-wrap"><span class="icon icon-theme-os-default "></span>Theme</span></button></div><ul class="auth-container"><li><a href="/users/fxa/login/authenticate/?next=%2Fen-US%2Fdocs%2FWeb%2FAPI%2FRequestInit" class="login-link" rel="nofollow">Log in</a></li><li><a href="/users/fxa/login/authenticate/?next=%2Fen-US%2Fdocs%2FWeb%2FAPI%2FRequestInit" target="_self" rel="nofollow" class="button primary mdn-plus-subscribe-link"><span class="button-wrap">Sign up for free</span></a></li></ul></div></div></header><div class="article-actions-container"><div class="container"><button type="button" class="button action has-icon sidebar-button" aria-label="Expand sidebar" aria-expanded="false" aria-controls="sidebar-quicklinks"><span class="button-wrap"><span class="icon icon-sidebar "></span></span></button><nav class="breadcrumbs-container" aria-label="Breadcrumb"><ol typeof="BreadcrumbList" vocab="https://schema.org/" aria-label="breadcrumbs"><li property="itemListElement" typeof="ListItem"><a href="/en-US/docs/Web" class="breadcrumb" property="item" typeof="WebPage"><span property="name">References</span></a><meta property="position" content="1"/></li><li property="itemListElement" typeof="ListItem"><a href="/en-US/docs/Web/API" class="breadcrumb" property="item" typeof="WebPage"><span property="name">Web APIs</span></a><meta property="position" content="2"/></li><li property="itemListElement" typeof="ListItem"><a href="/en-US/docs/Web/API/RequestInit" class="breadcrumb-current-page" property="item" typeof="WebPage"><span property="name">RequestInit</span></a><meta property="position" content="3"/></li></ol></nav><div class="article-actions"><button type="button" class="button action has-icon article-actions-toggle" aria-label="Article actions"><span class="button-wrap"><span class="icon icon-ellipses "></span><span class="article-actions-dialog-heading">Article Actions</span></span></button><ul class="article-actions-entries"><li class="article-actions-entry"><div class="languages-switcher-menu open-on-focus-within"><button id="languages-switcher-button" type="button" class="button action small has-icon languages-switcher-menu" aria-haspopup="menu"><span class="button-wrap"><span class="icon icon-language "></span>English (US)</span></button><div class="hidden"><ul class="submenu language-menu " aria-labelledby="language-menu-button"><li class=" "><form class="submenu-item locale-redirect-setting"><div class="group"><label class="switch"><input type="checkbox" name="locale-redirect"/><span class="slider"></span><span class="label">Remember language</span></label><a href="https://github.com/orgs/mdn/discussions/739" rel="external noopener noreferrer" target="_blank" title="Enable this setting to automatically switch to this language when it's available. (Click to learn more.)"><span class="icon icon-question-mark "></span></a></div></form></li><li class=" "><a data-locale="de" href="/de/docs/Web/API/RequestInit" class="button submenu-item"><span>Deutsch</span><span title="Diese Übersetzung ist Teil eines Experiments."><span class="icon icon-experimental "></span></span></a></li><li class=" "><a data-locale="ja" href="/ja/docs/Web/API/RequestInit" class="button submenu-item"><span>日本語</span></a></li></ul></div></div></li></ul></div></div></div></div><div class="main-wrapper"><div class="sidebar-container"><aside id="sidebar-quicklinks" class="sidebar" data-macro="APIRef"><button type="button" class="button action backdrop" aria-label="Collapse sidebar"><span class="button-wrap"></span></button><nav aria-label="Related Topics" class="sidebar-inner"><header class="sidebar-actions"><section class="sidebar-filter-container"><div class="sidebar-filter "><label id="sidebar-filter-label" class="sidebar-filter-label" for="sidebar-filter-input"><span class="icon icon-filter"></span><span class="visually-hidden">Filter sidebar</span></label><input id="sidebar-filter-input" autoComplete="off" class="sidebar-filter-input-field false" type="text" placeholder="Filter" value=""/><button type="button" class="button action has-icon clear-sidebar-filter-button"><span class="button-wrap"><span class="icon icon-cancel "></span><span class="visually-hidden">Clear filter input</span></span></button></div></section></header><div class="sidebar-inner-nav"><div class="in-nav-toc"><div class="document-toc-container"><section class="document-toc"><header><h2 class="document-toc-heading">In this article</h2></header><ul class="document-toc-list"><li class="document-toc-item "><a class="document-toc-link" href="#instance_properties">Instance properties</a></li><li class="document-toc-item "><a class="document-toc-link" href="#examples">Examples</a></li><li class="document-toc-item "><a class="document-toc-link" href="#specifications">Specifications</a></li><li class="document-toc-item "><a class="document-toc-link" href="#see_also">See also</a></li></ul></section></div></div><div class="sidebar-body"><ol><li class="section"><a href="/en-US/docs/Web/API/Fetch_API">Fetch API</a></li><li class="section"><em><a href="/en-US/docs/Web/API/RequestInit" aria-current="page"><code>RequestInit</code></a></em></li><li class="toggle"><details open=""><summary>Related pages for Fetch API</summary><ol><li><a href="/en-US/docs/Web/API/Headers"><code>Headers</code></a></li><li><a href="/en-US/docs/Web/API/Request"><code>Request</code></a></li><li><a href="/en-US/docs/Web/API/Response"><code>Response</code></a></li><li><a href="/en-US/docs/Web/API/Window/fetch"><code>Window.fetch()</code></a></li><li><a href="/en-US/docs/Web/API/WorkerGlobalScope/fetch"><code>WorkerGlobalScope.fetch()</code></a></li></ol></details></li></ol></div></div><section class="place side"></section></nav></aside><div class="toc-container"><aside class="toc"><nav><div class="document-toc-container"><section class="document-toc"><header><h2 class="document-toc-heading">In this article</h2></header><ul class="document-toc-list"><li class="document-toc-item "><a class="document-toc-link" href="#instance_properties">Instance properties</a></li><li class="document-toc-item "><a class="document-toc-link" href="#examples">Examples</a></li><li class="document-toc-item "><a class="document-toc-link" href="#specifications">Specifications</a></li><li class="document-toc-item "><a class="document-toc-link" href="#see_also">See also</a></li></ul></section></div></nav></aside><section class="place side"></section></div></div><main id="content" class="main-content "><article class="main-page-content" lang="en-US"><header><h1>RequestInit</h1></header><div class="section-content"><p>The <strong><code>RequestInit</code></strong> dictionary of the <a href="/en-US/docs/Web/API/Fetch_API">Fetch API</a> represents the set of options that can be used to configure a Fetch request.</p> <p>You can pass a <code>RequestInit</code> object into the <a href="/en-US/docs/Web/API/Request/Request" title="Request()"><code>Request()</code></a> constructor, or directly into the <a href="/en-US/docs/Web/API/Window/fetch"><code>fetch()</code></a> function call.</p> <p>You can also construct a <code>Request</code> with a <code>RequestInit</code>, and pass the <code>Request</code> to a <code>fetch()</code> call along with another <code>RequestInit</code>. If you do this, and the same option is set in both places, then the value passed directly into <code>fetch()</code> is used.</p></div><section aria-labelledby="instance_properties"><h2 id="instance_properties"><a href="#instance_properties">Instance properties</a></h2><div class="section-content"><dl> <dt id="attributionreporting"><a href="#attributionreporting"><code>attributionReporting</code></a> <span class="badge inline optional">Optional</span> <abbr class="icon icon-experimental" title="Experimental. Expect behavior to change in the future."> <span class="visually-hidden">Experimental</span> </abbr></dt> <dd> <p>Indicates that you want the request's response to be able to register a JavaScript-based <a href="/en-US/docs/Web/API/Attribution_Reporting_API/Registering_sources#javascript-based_event_sources">attribution source</a> or <a href="/en-US/docs/Web/API/Attribution_Reporting_API/Registering_triggers#javascript-based_attribution_triggers">attribution trigger</a>. <code>attributionReporting</code> is an object containing the following properties:</p> <dl> <dt id="eventsourceeligible"><a href="#eventsourceeligible"><code>eventSourceEligible</code></a></dt> <dd> <p>A boolean. If set to <code>true</code>, the request's response is eligible to register an attribution source. If set to <code>false</code>, it isn't.</p> </dd> <dt id="triggereligible"><a href="#triggereligible"><code>triggerEligible</code></a></dt> <dd> <p>A boolean. If set to <code>true</code>, the request's response is eligible to register an attribution trigger. If set to <code>false</code>, it isn't.</p> </dd> </dl> <p>See the <a href="/en-US/docs/Web/API/Attribution_Reporting_API">Attribution Reporting API</a> for more details.</p> </dd> <dt id="body"><a href="#body"><code>body</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>The request body contains content to send to the server, for example in a <a href="/en-US/docs/Web/HTTP/Methods/POST"><code>POST</code></a> or <a href="/en-US/docs/Web/HTTP/Methods/PUT"><code>PUT</code></a> request. It is specified as an instance of any of the following types:</p> <ul> <li>a string</li> <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer"><code>ArrayBuffer</code></a></li> <li><a href="/en-US/docs/Web/API/Blob"><code>Blob</code></a></li> <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView"><code>DataView</code></a></li> <li><a href="/en-US/docs/Web/API/File"><code>File</code></a></li> <li><a href="/en-US/docs/Web/API/FormData"><code>FormData</code></a></li> <li><a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray"><code>TypedArray</code></a></li> <li><a href="/en-US/docs/Web/API/URLSearchParams"><code>URLSearchParams</code></a></li> <li><a href="/en-US/docs/Web/API/ReadableStream"><code>ReadableStream</code></a></li> </ul> <p>See <a href="/en-US/docs/Web/API/Fetch_API/Using_Fetch#setting_a_body">Setting a body</a> for more details.</p> </dd> <dt id="browsingtopics"><a href="#browsingtopics"><code>browsingTopics</code></a> <span class="badge inline optional">Optional</span> <abbr class="icon icon-experimental" title="Experimental. Expect behavior to change in the future."> <span class="visually-hidden">Experimental</span> </abbr></dt> <dd> <p>A boolean specifying that the selected topics for the current user should be sent in a <a href="/en-US/docs/Web/HTTP/Headers/Sec-Browsing-Topics"><code>Sec-Browsing-Topics</code></a> header with the associated request.</p> <p>See <a href="/en-US/docs/Web/API/Topics_API/Using">Using the Topics API</a> for more details.</p> </dd> <dt id="cache"><a href="#cache"><code>cache</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>The <a href="/en-US/docs/Web/API/Request/cache">cache mode</a> you want to use for the request. This may be any one of the following values:</p> <dl> <dt id="default"><a href="#default"><code>default</code></a></dt> <dd> <p>The browser looks in its HTTP cache for a response matching the request.</p> <ul> <li>If there is a match and it is <a href="/en-US/docs/Web/HTTP/Caching#fresh_and_stale_based_on_age">fresh</a>, it will be returned from the cache.</li> <li>If there is a match but it is <a href="/en-US/docs/Web/HTTP/Caching#fresh_and_stale_based_on_age">stale</a>, the browser will make a <a href="/en-US/docs/Web/HTTP/Conditional_requests">conditional request</a> to the remote server. If the server indicates that the resource has not changed, it will be returned from the cache. Otherwise the resource will be downloaded from the server and the cache will be updated.</li> <li>If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.</li> </ul> </dd> <dt id="no-store"><a href="#no-store"><code>no-store</code></a></dt> <dd> <p>The browser fetches the resource from the remote server without first looking in the cache, <em>and will not</em> update the cache with the downloaded resource.</p> </dd> <dt id="reload"><a href="#reload"><code>reload</code></a></dt> <dd> <p>The browser fetches the resource from the remote server without first looking in the cache, <em>but then will</em> update the cache with the downloaded resource.</p> </dd> <dt id="no-cache"><a href="#no-cache"><code>no-cache</code></a></dt> <dd> <p>The browser looks in its HTTP cache for a response matching the request.</p> <ul> <li>If there is a match, <em>fresh or stale,</em> the browser will make a <a href="/en-US/docs/Web/HTTP/Conditional_requests">conditional request</a> to the remote server. If the server indicates that the resource has not changed, it will be returned from the cache. Otherwise the resource will be downloaded from the server and the cache will be updated.</li> <li>If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.</li> </ul> </dd> <dt id="force-cache"><a href="#force-cache"><code>force-cache</code></a></dt> <dd> <p>The browser looks in its HTTP cache for a response matching the request.</p> <ul> <li>If there is a match, <em>fresh or stale</em>, it will be returned from the cache.</li> <li>If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.</li> </ul> </dd> <dt id="only-if-cached"><a href="#only-if-cached"><code>only-if-cached</code></a></dt> <dd> <p>The browser looks in its HTTP cache for a response matching the request. <abbr class="icon icon-experimental" title="Experimental. Expect behavior to change in the future."> <span class="visually-hidden">Experimental</span> </abbr></p> <ul> <li>If there is a match, <em>fresh or stale</em>, it will be returned from the cache.</li> <li>If there is no match, a network error is returned.</li> </ul> </dd> </dl> <p>The <code>"only-if-cached"</code> mode can only be used if the request's <a href="/en-US/docs/Web/API/Request/mode"><code>mode</code></a> is <code>"same-origin"</code>. Cached redirects will be followed if the request's <code>redirect</code> property is <code>"follow"</code> and the redirects do not violate the <code>"same-origin"</code> mode.</p> </dd> <dt id="credentials"><a href="#credentials"><code>credentials</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>Controls whether or not the browser sends credentials with the request, as well as whether any <strong><code>Set-Cookie</code></strong> response headers are respected. Credentials are cookies, <a href="/en-US/docs/Glossary/TLS">TLS</a> client certificates, or authentication headers containing a username and password. This option may be any one of the following values:</p> <dl> <dt id="omit"><a href="#omit"><code>omit</code></a></dt> <dd> <p>Never send credentials in the request or include credentials in the response.</p> </dd> <dt id="same-origin"><a href="#same-origin"><code>same-origin</code></a></dt> <dd> <p>Only send and include credentials for same-origin requests.</p> </dd> <dt id="include"><a href="#include"><code>include</code></a></dt> <dd> <p>Always include credentials, even for cross-origin requests.</p> </dd> </dl> <p>Including credentials in cross-origin requests can make a site vulnerable to <a href="/en-US/docs/Glossary/CSRF">CSRF</a> attacks, so even if <code>credentials</code> is set to <code>include</code>, the server must also agree to their inclusion by including the <a href="/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials"><code>Access-Control-Allow-Credentials</code></a> in its response. Additionally, in this situation the server must explicitly specify the client's origin in the <a href="/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin"><code>Access-Control-Allow-Origin</code></a> response header (that is, <code>*</code> is not allowed).</p> <p>See <a href="/en-US/docs/Web/API/Fetch_API/Using_Fetch#including_credentials">Including credentials</a> for more details.</p> <p>Defaults to <code>same-origin</code>.</p> </dd> <dt id="headers"><a href="#headers"><code>headers</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p> Any headers you want to add to your request, contained within a <a href="/en-US/docs/Web/API/Headers"><code>Headers</code></a> object or an object literal whose keys are the names of headers and whose values are the header values. </p> <p>Many headers are set automatically by the browser and can't be set by a script: these are called <a href="/en-US/docs/Glossary/Forbidden_header_name">Forbidden header names</a>.</p> <p>If the <code>mode</code> option is set to <code>no-cors</code>, you can only set <a href="/en-US/docs/Glossary/CORS-safelisted_request_header">CORS-safelisted request headers</a>.</p> <p>See <a href="/en-US/docs/Web/API/Fetch_API/Using_Fetch#setting_headers">Setting headers</a> for more details.</p> </dd> <dt id="integrity"><a href="#integrity"><code>integrity</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p> Contains the <a href="/en-US/docs/Web/Security/Subresource_Integrity">subresource integrity</a> value of the request. </p> <p>This will be checked when the resource is fetched, just as it would be when the <a href="/en-US/docs/Web/HTML/Element/script#integrity"><code>integrity</code></a> attribute is set on a <a href="/en-US/docs/Web/HTML/Element/script"><code><script></code></a> element. The browser will compute the <a href="/en-US/docs/Glossary/Cryptographic_hash_function">hash</a> of the fetched resource using the specified algorithm, and if the result does not match the value specified, the browser will reject the fetch request with a network error.</p> <p>The format of this option is <code><hash-algo>-<hash-source></code> where:</p> <ul> <li><code><hash-algo></code> is one of the following values: <code>sha256</code>, <code>sha384</code>, or <code>sha512</code></li> <li><code><hash-source></code> is the <a href="/en-US/docs/Glossary/Base64">Base64-encoding</a> of the result of hashing the resource with the specified hash algorithm.</li> </ul> <p>Defaults to an empty string.</p> </dd> <dt id="keepalive"><a href="#keepalive"><code>keepalive</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>A boolean. When set to <code>true</code>, the browser will not abort the associated request if the page that initiated it is unloaded before the request is complete. This enables a <a href="/en-US/docs/Web/API/Window/fetch" title="fetch()"><code>fetch()</code></a> request to function as an alternative to <a href="/en-US/docs/Web/API/Navigator/sendBeacon"><code>Navigator.sendBeacon()</code></a> when sending analytics at the end of a session, which has some advantages (you can use HTTP methods other than <a href="/en-US/docs/Web/HTTP/Methods/POST"><code>POST</code></a>, customize request properties, and access the server response via the fetch <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise"><code>Promise</code></a> fulfillment). It is also available in <a href="/en-US/docs/Web/API/Service_Worker_API">service workers</a>.</p> <p>The body size for <code>keepalive</code> requests is limited to 64 kibibytes.</p> <p>Defaults to <code>false</code>.</p> </dd> <dt id="method"><a href="#method"><code>method</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>The <a href="/en-US/docs/Web/HTTP/Methods">request method</a>.</p> <p>Defaults to <a href="/en-US/docs/Web/HTTP/Methods/GET"><code>GET</code></a>.</p> </dd> <dt id="mode"><a href="#mode"><code>mode</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>Sets cross-origin behavior for the request. One of the following values:</p> <dl> <dt id="same-origin_2"><a href="#same-origin_2"><code>same-origin</code></a></dt> <dd> <p>Disallows cross-origin requests. If a <code>same-origin</code> request is sent to a different origin, the result is a network error.</p> </dd> <dt id="cors"><a href="#cors"><code>cors</code></a></dt> <dd> <p>If the request is cross-origin then it will use the <a href="/en-US/docs/Web/HTTP/CORS">Cross-Origin Resource Sharing (CORS)</a> mechanism. Only <a href="/en-US/docs/Glossary/CORS-safelisted_response_header">CORS-safelisted response headers</a> are exposed in the response.</p> </dd> <dt id="no-cors"><a href="#no-cors"><code>no-cors</code></a></dt> <dd> <p>Disables CORS for cross-origin requests. This option comes with the following restrictions:</p> <ul> <li>The method may only be one of <code>HEAD</code>, <code>GET</code> or <code>POST</code>.</li> <li>The headers may only be <a href="/en-US/docs/Glossary/CORS-safelisted_request_header">CORS-safelisted request headers</a>, with the additional restriction that the <a href="/en-US/docs/Web/HTTP/Headers/Range"><code>Range</code></a> header is also not allowed. This also applies to any headers added by service workers.</li> <li>The response is <em>opaque</em>, meaning that its headers and body are not available to JavaScript, and its <a href="/en-US/docs/Web/API/Response/status" title="status code">status code</a> is always <code>0</code>.</li> </ul> <p>The main application for <code>no-cors</code> is for a service worker: although the response to a <code>no-cors</code> request can't be read by JavaScript, it can be cached by a service worker and then used as a response to an intercepted fetch request. Note that in this situation you don't know whether the request succeeded or not, so you should adopt a caching strategy which enables the cached response to be updated from the network (such as <a href="/en-US/docs/Web/Progressive_web_apps/Guides/Caching#cache_first_with_cache_refresh">cache first with cache refresh</a>).</p> </dd> <dt id="navigate"><a href="#navigate"><code>navigate</code></a></dt> <dd> <p>Used only by HTML navigation. A <code>navigate</code> request is created only while navigating between documents.</p> </dd> </dl> <p>See <a href="/en-US/docs/Web/API/Fetch_API/Using_Fetch#making_cross-origin_requests">Making cross-origin requests</a> for more details.</p> <p>Defaults to <code>cors</code>.</p> </dd> <dt id="priority"><a href="#priority"><code>priority</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>Specifies the priority of the fetch request relative to other requests of the same type. Must be one of the following:</p> <dl> <dt id="high"><a href="#high"><code>high</code></a></dt> <dd> <p>A high priority fetch request relative to other requests of the same type.</p> </dd> <dt id="low"><a href="#low"><code>low</code></a></dt> <dd> <p>A low priority fetch request relative to other requests of the same type.</p> </dd> <dt id="auto"><a href="#auto"><code>auto</code></a></dt> <dd> <p> No user preference for the fetch priority. It is used if no value is set or if an invalid value is set. </p> </dd> </dl> <p>Defaults to <code>auto</code>.</p> </dd> <dt id="redirect"><a href="#redirect"><code>redirect</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>Determines the browser's behavior in case the server replies with a <a href="/en-US/docs/Web/HTTP/Status#redirection_messages">redirect status</a>. One of the following values:</p> <dl> <dt id="follow"><a href="#follow"><code>follow</code></a></dt> <dd> <p>Automatically follow redirects.</p> </dd> <dt id="error"><a href="#error"><code>error</code></a></dt> <dd> <p>Reject the promise with a network error when a redirect status is returned.</p> </dd> <dt id="manual"><a href="#manual"><code>manual</code></a></dt> <dd> <p>Return a response with almost all fields filtered out, to enable a service worker to store the response and later replay it.</p> </dd> </dl> <p>Defaults to <code>follow</code>.</p> </dd> <dt id="referrer"><a href="#referrer"><code>referrer</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>A string specifying the value to use for the request's <a href="/en-US/docs/Web/HTTP/Headers/Referer"><code>Referer</code></a> header. One of the following:</p> <dl> <dt id="a_same-origin_relative_or_absolute_url"><a href="#a_same-origin_relative_or_absolute_url">A same-origin relative or absolute URL</a></dt> <dd> <p>Set the <code>Referer</code> header to the given value. Relative URLs are resolved relative to the URL of the page that made the request.</p> </dd> <dt id="an_empty_string"><a href="#an_empty_string">An empty string</a></dt> <dd> <p>Omit the <code>Referer</code> header.</p> </dd> <dt id="aboutclient"><a href="#aboutclient"><code>about:client</code></a></dt> <dd> <p>Set the <code>Referer</code> header to the default value for the context of the request (for example, the URL of the page that made the request).</p> </dd> </dl> <p>Defaults to <code>about:client</code>.</p> </dd> <dt id="referrerpolicy"><a href="#referrerpolicy"><code>referrerPolicy</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>A string that sets a policy for the <a href="/en-US/docs/Web/HTTP/Headers/Referer"><code>Referer</code></a> header. The syntax and semantics of this option are exactly the same as for the <a href="/en-US/docs/Web/HTTP/Headers/Referrer-Policy"><code>Referrer-Policy</code></a> header.</p> </dd> <dt id="signal"><a href="#signal"><code>signal</code></a> <span class="badge inline optional">Optional</span></dt> <dd> <p>An <a href="/en-US/docs/Web/API/AbortSignal"><code>AbortSignal</code></a>. If this option is set, the request can be canceled by calling <a href="/en-US/docs/Web/API/AbortController/abort" title="abort()"><code>abort()</code></a> on the corresponding <code>AbortController</code>.</p> </dd> </dl></div></section><section aria-labelledby="examples"><h2 id="examples"><a href="#examples">Examples</a></h2><div class="section-content"></div></section><section aria-labelledby="passing_options_into_fetch"><h3 id="passing_options_into_fetch"><a href="#passing_options_into_fetch">Passing options into <code>fetch()</code></a></h3><div class="section-content"><p>In this example we pass the <code>method</code>, <code>body</code>, and <code>headers</code> options directly into the <a href="/en-US/docs/Web/API/Window/fetch"><code>fetch()</code></a> method call:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>async function post() { const response = await fetch("https://example.org/post", { method: "POST", body: JSON.stringify({ username: "example" }), headers: { "Content-Type": "application/json", }, }); console.log(response.status); } </code></pre></div></div></section><section aria-labelledby="passing_options_into_the_request_constructor"><h3 id="passing_options_into_the_request_constructor"><a href="#passing_options_into_the_request_constructor">Passing options into the <code>Request()</code> constructor</a></h3><div class="section-content"><p>In this example we create a <a href="/en-US/docs/Web/API/Request"><code>Request</code></a>, passing the same set of options into its constructor, and then pass the request into <code>fetch()</code>:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>async function post() { const request = new Request("https://example.org/post", { method: "POST", body: JSON.stringify({ username: "example" }), headers: { "Content-Type": "application/json", }, }); const response = await fetch(request); console.log(response.status); } </code></pre></div></div></section><section aria-labelledby="passing_options_into_both_request_and_fetch"><h3 id="passing_options_into_both_request_and_fetch"><a href="#passing_options_into_both_request_and_fetch">Passing options into both <code>Request()</code> and <code>fetch()</code></a></h3><div class="section-content"><p>In this example we create a <a href="/en-US/docs/Web/API/Request"><code>Request</code></a>, passing the <code>method</code>, <code>headers</code>, and <code>body</code> options into its constructor. We then pass the request into <code>fetch()</code> along with <code>body</code> and <code>referrer</code> options:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>async function post() { const request = new Request("https://example.org/post", { method: "POST", headers: { "Content-Type": "application/json", }, body: JSON.stringify({ username: "example1" }), }); const response = await fetch(request, { body: JSON.stringify({ username: "example2" }), referrer: "", }); console.log(response.status); } </code></pre></div> <p>In this case the request will be sent with the following options:</p> <ul> <li><code>method: "POST"</code></li> <li><code>headers: {"Content-Type": "application/json"}</code></li> <li><code>body: '{"username":"example2"}'</code></li> <li><code>referrer: ""</code></li> </ul></div></section><h2 id="specifications"><a href="#specifications">Specifications</a></h2><table class="standard-table"><thead><tr><th scope="col">Specification</th></tr></thead><tbody><tr><td><a href="https://fetch.spec.whatwg.org/#requestinit">Fetch Standard <br/><small># requestinit</small></a></td></tr></tbody></table><section aria-labelledby="see_also"><h2 id="see_also"><a href="#see_also">See also</a></h2><div class="section-content"><ul> <li><a href="/en-US/docs/Web/API/Fetch_API/Using_Fetch">Using Fetch</a></li> <li><a href="/en-US/docs/Web/API/Service_Worker_API">ServiceWorker API</a></li> <li><a href="/en-US/docs/Web/HTTP/CORS">HTTP access control (CORS)</a></li> <li><a href="/en-US/docs/Web/HTTP">HTTP</a></li> </ul></div></section></article><aside class="article-footer"><div class="article-footer-inner"><div class="svg-container"><svg xmlns="http://www.w3.org/2000/svg" width="162" height="162" viewBox="0 0 162 162" fill="none" role="none"><mask id="b" fill="#fff"><path d="M97.203 47.04c8.113-7.886 18.004-13.871 28.906-17.492a78 78 0 0 1 33.969-3.39c11.443 1.39 22.401 5.295 32.024 11.411s17.656 14.28 23.476 23.86c5.819 9.579 9.269 20.318 10.083 31.385a69.85 69.85 0 0 1-5.387 32.44c-4.358 10.272-11.115 19.443-19.747 26.801-8.632 7.359-18.908 12.709-30.034 15.637l-6.17-21.698c7.666-2.017 14.746-5.703 20.694-10.773 5.948-5.071 10.603-11.389 13.606-18.467a48.14 48.14 0 0 0 3.712-22.352c-.561-7.625-2.938-15.025-6.948-21.625s-9.544-12.226-16.175-16.44-14.181-6.904-22.065-7.863a53.75 53.75 0 0 0-23.405 2.336c-7.513 2.495-14.327 6.62-19.918 12.053z"></path></mask><path stroke="url(#a)" stroke-dasharray="6, 6" stroke-width="2" d="M97.203 47.04c8.113-7.886 18.004-13.871 28.906-17.492a78 78 0 0 1 33.969-3.39c11.443 1.39 22.401 5.295 32.024 11.411s17.656 14.28 23.476 23.86c5.819 9.579 9.269 20.318 10.083 31.385a69.85 69.85 0 0 1-5.387 32.44c-4.358 10.272-11.115 19.443-19.747 26.801-8.632 7.359-18.908 12.709-30.034 15.637l-6.17-21.698c7.666-2.017 14.746-5.703 20.694-10.773 5.948-5.071 10.603-11.389 13.606-18.467a48.14 48.14 0 0 0 3.712-22.352c-.561-7.625-2.938-15.025-6.948-21.625s-9.544-12.226-16.175-16.44-14.181-6.904-22.065-7.863a53.75 53.75 0 0 0-23.405 2.336c-7.513 2.495-14.327 6.62-19.918 12.053z" mask="url(#b)" style="stroke:url(#a)" transform="translate(-63.992 -25.587)"></path><ellipse cx="8.066" cy="111.597" fill="var(--background-tertiary)" rx="53.677" ry="53.699" transform="matrix(.71707 -.697 .7243 .6895 0 0)"></ellipse><g clip-path="url(#c)" transform="translate(-63.992 -25.587)"><path fill="#9abff5" d="m144.256 137.379 32.906 12.434a4.41 4.41 0 0 1 2.559 5.667l-9.326 24.679a4.41 4.41 0 0 1-5.667 2.559l-8.226-3.108-2.332 6.17c-.466 1.233-.375 1.883-1.609 1.417l-2.253-.527c-.411-.155-.95-.594-1.206-1.161l-4.734-10.484-12.545-4.741a4.41 4.41 0 0 1-2.559-5.667l9.325-24.679a4.41 4.41 0 0 1 5.667-2.559m9.961 29.617 8.227 3.108 3.264-8.638-.498-6.768-4.113-1.555.548 7.258-4.319-1.632zm-12.339-4.663 8.226 3.108 3.264-8.637-.498-6.769-4.113-1.554.548 7.257-4.319-1.632z"></path></g><g clip-path="url(#d)" transform="translate(-63.992 -25.587)"><path fill="#81b0f3" d="M135.35 60.136 86.67 41.654c-3.346-1.27-7.124.428-8.394 3.775L64.414 81.938c-1.27 3.347.428 7.125 3.774 8.395l12.17 4.62-3.465 9.128c-.693 1.826-1.432 2.457.394 3.15l3.014 1.625c.609.231 1.637.274 2.477-.104l15.53-6.983 18.56 7.047c3.346 1.27 7.124-.428 8.395-3.775l13.862-36.51c1.27-3.346-.428-7.124-3.775-8.395M95.261 83.207l-12.17-4.62 4.852-12.779 7.19-7.017 6.085 2.31-7.725 7.51 6.389 2.426zm18.255 6.93-12.17-4.62 4.852-12.778 7.189-7.017 6.085 2.31-7.725 7.51 6.39 2.426z"></path></g><defs><clipPath id="c"><path fill="#fff" d="m198.638 146.586-65.056-24.583-24.583 65.057 65.056 24.582z"></path></clipPath><clipPath id="d"><path fill="#fff" d="m66.438 14.055 96.242 36.54-36.54 96.243-96.243-36.54z"></path></clipPath><linearGradient id="a" x1="97.203" x2="199.995" y1="47.04" y2="152.793" gradientUnits="userSpaceOnUse"><stop stop-color="#086DFC"></stop><stop offset="0.246" stop-color="#2C81FA"></stop><stop offset="0.516" stop-color="#5497F8"></stop><stop offset="0.821" stop-color="#80B0F6"></stop><stop offset="1" stop-color="#9ABFF5"></stop></linearGradient></defs></svg></div><h2>Help improve MDN</h2><fieldset class="feedback"><label>Was this page helpful to you?</label><div class="button-container"><button type="button" class="button primary has-icon yes"><span class="button-wrap"><span class="icon icon-thumbs-up "></span>Yes</span></button><button type="button" class="button primary has-icon no"><span class="button-wrap"><span class="icon icon-thumbs-down "></span>No</span></button></div></fieldset><a class="contribute" href="https://github.com/mdn/content/blob/main/CONTRIBUTING.md" title="This will take you to our contribution guidelines on GitHub." target="_blank" rel="noopener noreferrer">Learn how to contribute</a>.<p class="last-modified-date">This page was last modified on <time dateTime="2024-10-31T04:58:07.000Z">Oct 31, 2024</time> by <a href="/en-US/docs/Web/API/RequestInit/contributors.txt" rel="nofollow">MDN contributors</a>.</p><div id="on-github" class="on-github"><a href="https://github.com/mdn/content/blob/main/files/en-us/web/api/requestinit/index.md?plain=1" title="Folder: en-us/web/api/requestinit (Opens in a new tab)" target="_blank" rel="noopener noreferrer">View this page on GitHub</a> • <a href="https://github.com/mdn/content/issues/new?template=page-report.yml&mdn-url=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FAPI%2FRequestInit&metadata=%3C%21--+Do+not+make+changes+below+this+line+--%3E%0A%3Cdetails%3E%0A%3Csummary%3EPage+report+details%3C%2Fsummary%3E%0A%0A*+Folder%3A+%60en-us%2Fweb%2Fapi%2Frequestinit%60%0A*+MDN+URL%3A+https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FAPI%2FRequestInit%0A*+GitHub+URL%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fblob%2Fmain%2Ffiles%2Fen-us%2Fweb%2Fapi%2Frequestinit%2Findex.md%0A*+Last+commit%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fcommit%2F22526bdf0076aec093ba0a1ba32a6bb0d4ffd853%0A*+Document+last+modified%3A+2024-10-31T04%3A58%3A07.000Z%0A%0A%3C%2Fdetails%3E" title="This will take you to GitHub to file a new issue." target="_blank" rel="noopener noreferrer">Report a problem with this content</a></div></div></aside></main></div></div><footer id="nav-footer" class="page-footer"><div class="page-footer-grid"><div class="page-footer-logo-col"><a href="/" class="mdn-footer-logo" aria-label="MDN homepage"><svg width="48" height="17" viewBox="0 0 48 17" fill="none" xmlns="http://www.w3.org/2000/svg"><title id="mdn-footer-logo-svg">MDN logo</title><path d="M20.04 16.512H15.504V10.416C15.504 9.488 15.344 8.824 15.024 8.424C14.72 8.024 14.264 7.824 13.656 7.824C12.92 7.824 12.384 8.064 12.048 8.544C11.728 9.024 11.568 9.64 11.568 10.392V14.184H13.008V16.512H8.472V10.416C8.472 9.488 8.312 8.824 7.992 8.424C7.688 8.024 7.232 7.824 6.624 7.824C5.872 7.824 5.336 8.064 5.016 8.544C4.696 9.024 4.536 9.64 4.536 10.392V14.184H6.6V16.512H0V14.184H1.44V8.04H0.024V5.688H4.536V7.32C5.224 6.088 6.32 5.472 7.824 5.472C8.608 5.472 9.328 5.664 9.984 6.048C10.64 6.432 11.096 7.016 11.352 7.8C11.992 6.248 13.168 5.472 14.88 5.472C15.856 5.472 16.72 5.776 17.472 6.384C18.224 6.992 18.6 7.936 18.6 9.216V14.184H20.04V16.512Z" fill="currentColor"></path><path d="M33.6714 16.512H29.1354V14.496C28.8314 15.12 28.3834 15.656 27.7914 16.104C27.1994 16.536 26.4154 16.752 25.4394 16.752C24.0154 16.752 22.8954 16.264 22.0794 15.288C21.2634 14.312 20.8554 12.984 20.8554 11.304C20.8554 9.688 21.2554 8.312 22.0554 7.176C22.8554 6.04 24.0634 5.472 25.6794 5.472C26.5594 5.472 27.2794 5.648 27.8394 6C28.3994 6.352 28.8314 6.8 29.1354 7.344V2.352H26.9754V0H32.2314V14.184H33.6714V16.512ZM29.1354 11.04V10.776C29.1354 9.88 28.8954 9.184 28.4154 8.688C27.9514 8.176 27.3674 7.92 26.6634 7.92C25.9754 7.92 25.3674 8.176 24.8394 8.688C24.3274 9.2 24.0714 10.008 24.0714 11.112C24.0714 12.152 24.3114 12.944 24.7914 13.488C25.2714 14.032 25.8394 14.304 26.4954 14.304C27.3114 14.304 27.9514 13.96 28.4154 13.272C28.8954 12.584 29.1354 11.84 29.1354 11.04Z" fill="currentColor"></path><path d="M47.9589 16.512H41.9829V14.184H43.4229V10.416C43.4229 9.488 43.2629 8.824 42.9429 8.424C42.6389 8.024 42.1829 7.824 41.5749 7.824C40.8389 7.824 40.2709 8.056 39.8709 8.52C39.4709 8.968 39.2629 9.56 39.2469 10.296V14.184H40.6869V16.512H34.7109V14.184H36.1509V8.04H34.5909V5.688H39.2469V7.344C39.9669 6.096 41.1269 5.472 42.7269 5.472C43.7509 5.472 44.6389 5.776 45.3909 6.384C46.1429 6.992 46.5189 7.936 46.5189 9.216V14.184H47.9589V16.512Z" fill="currentColor"></path></svg></a><p>Your blueprint for a better internet.</p><ul class="social-icons"><li><a href="https://mozilla.social/@mdn" target="_blank" rel="me noopener noreferrer"><span class="icon icon-mastodon"></span><span class="visually-hidden">MDN on Mastodon</span></a></li><li><a href="https://twitter.com/mozdevnet" target="_blank" rel="noopener noreferrer"><span class="icon icon-twitter-x"></span><span class="visually-hidden">MDN on X (formerly Twitter)</span></a></li><li><a href="https://github.com/mdn/" target="_blank" rel="noopener noreferrer"><span class="icon icon-github-mark-small"></span><span class="visually-hidden">MDN on GitHub</span></a></li><li><a href="/en-US/blog/rss.xml" target="_blank"><span class="icon icon-feed"></span><span class="visually-hidden">MDN Blog RSS Feed</span></a></li></ul></div><div class="page-footer-nav-col-1"><h2 class="footer-nav-heading">MDN</h2><ul class="footer-nav-list"><li class="footer-nav-item"><a href="/en-US/about">About</a></li><li class="footer-nav-item"><a href="/en-US/blog/">Blog</a></li><li class="footer-nav-item"><a href="https://www.mozilla.org/en-US/careers/listings/?team=ProdOps" target="_blank" rel="noopener noreferrer">Careers</a></li><li class="footer-nav-item"><a href="/en-US/advertising">Advertise with us</a></li></ul></div><div class="page-footer-nav-col-2"><h2 class="footer-nav-heading">Support</h2><ul class="footer-nav-list"><li class="footer-nav-item"><a class="footer-nav-link" href="https://support.mozilla.org/products/mdn-plus">Product help</a></li><li class="footer-nav-item"><a class="footer-nav-link" href="/en-US/docs/MDN/Community/Issues">Report an issue</a></li></ul></div><div class="page-footer-nav-col-3"><h2 class="footer-nav-heading">Our communities</h2><ul class="footer-nav-list"><li class="footer-nav-item"><a class="footer-nav-link" href="/en-US/community">MDN Community</a></li><li class="footer-nav-item"><a class="footer-nav-link" href="https://discourse.mozilla.org/c/mdn/236" target="_blank" rel="noopener noreferrer">MDN Forum</a></li><li class="footer-nav-item"><a class="footer-nav-link" href="/discord" target="_blank" rel="noopener noreferrer">MDN Chat</a></li></ul></div><div class="page-footer-nav-col-4"><h2 class="footer-nav-heading">Developers</h2><ul class="footer-nav-list"><li class="footer-nav-item"><a class="footer-nav-link" href="/en-US/docs/Web">Web Technologies</a></li><li class="footer-nav-item"><a class="footer-nav-link" href="/en-US/docs/Learn">Learn Web Development</a></li><li class="footer-nav-item"><a class="footer-nav-link" href="/en-US/plus">MDN Plus</a></li><li class="footer-nav-item"><a href="https://hacks.mozilla.org/" target="_blank" rel="noopener noreferrer">Hacks Blog</a></li></ul></div><div class="page-footer-moz"><a href="https://www.mozilla.org/" class="footer-moz-logo-link" target="_blank" rel="noopener noreferrer"><svg width="112" height="32" fill="none" xmlns="http://www.w3.org/2000/svg"><title id="mozilla-footer-logo-svg">Mozilla logo</title><path d="M41.753 14.218c-2.048 0-3.324 1.522-3.324 4.157 0 2.423 1.119 4.286 3.29 4.286 2.082 0 3.447-1.678 3.447-4.347 0-2.826-1.522-4.096-3.413-4.096Zm54.89 7.044c0 .901.437 1.618 1.645 1.618 1.427 0 2.949-1.024 3.044-3.352-.649-.095-1.365-.185-2.02-.185-1.426-.005-2.668.397-2.668 1.92Z" fill="currentColor"></path><path d="M0 0v32h111.908V0H0Zm32.56 25.426h-5.87v-7.884c0-2.423-.806-3.352-2.39-3.352-1.924 0-2.702 1.365-2.702 3.324v4.868h1.864v3.044h-5.864v-7.884c0-2.423-.806-3.352-2.39-3.352-1.924 0-2.702 1.365-2.702 3.324v4.868h2.669v3.044H6.642v-3.044h1.863v-7.918H6.642V11.42h5.864v2.11c.839-1.489 2.3-2.39 4.252-2.39 2.02 0 3.878.963 4.566 3.01.778-1.862 2.361-3.01 4.566-3.01 2.512 0 4.812 1.522 4.812 4.84v6.402h1.863v3.044h-.005Zm9.036.307c-4.314 0-7.296-2.635-7.296-7.106 0-4.096 2.484-7.481 7.514-7.481s7.481 3.38 7.481 7.29c0 4.472-3.228 7.297-7.699 7.297Zm22.578-.307H51.942l-.403-2.11 7.7-8.846h-4.376l-.621 2.17-2.888-.313.498-4.907h12.294l.313 2.11-7.767 8.852h4.533l.654-2.172 3.167.308-.872 4.908Zm7.99 0h-4.191v-5.03h4.19v5.03Zm0-8.976h-4.191v-5.03h4.19v5.03Zm2.618 8.976 6.054-21.358h3.945l-6.054 21.358h-3.945Zm8.136 0 6.048-21.358h3.945l-6.054 21.358h-3.939Zm21.486.307c-1.863 0-2.887-1.085-3.072-2.792-.805 1.427-2.232 2.792-4.498 2.792-2.02 0-4.314-1.085-4.314-4.006 0-3.447 3.323-4.253 6.518-4.253.778 0 1.584.034 2.3.124v-.465c0-1.427-.034-3.133-2.3-3.133-.84 0-1.488.061-2.143.402l-.453 1.578-3.195-.34.549-3.224c2.45-.996 3.692-1.27 5.992-1.27 3.01 0 5.556 1.55 5.556 4.75v6.083c0 .805.314 1.085.963 1.085.184 0 .375-.034.587-.095l.034 2.11a5.432 5.432 0 0 1-2.524.654Z" fill="currentColor"></path></svg></a><ul class="footer-moz-list"><li class="footer-moz-item"><a href="https://www.mozilla.org/privacy/websites/" class="footer-moz-link" target="_blank" rel="noopener noreferrer">Website Privacy Notice</a></li><li class="footer-moz-item"><a href="https://www.mozilla.org/privacy/websites/#cookies" class="footer-moz-link" target="_blank" rel="noopener noreferrer">Cookies</a></li><li class="footer-moz-item"><a href="https://www.mozilla.org/about/legal/terms/mozilla" class="footer-moz-link" target="_blank" rel="noopener noreferrer">Legal</a></li><li class="footer-moz-item"><a href="https://www.mozilla.org/about/governance/policies/participation/" class="footer-moz-link" target="_blank" rel="noopener noreferrer">Community Participation Guidelines</a></li></ul></div><div class="page-footer-legal"><p id="license" class="page-footer-legal-text">Visit <a href="https://www.mozilla.org" target="_blank" rel="noopener noreferrer">Mozilla Corporation’s</a> not-for-profit parent, the <a target="_blank" rel="noopener noreferrer" href="https://foundation.mozilla.org/">Mozilla Foundation</a>.<br/>Portions of this content are ©1998–2024 by individual mozilla.org contributors. Content available under <a href="/en-US/docs/MDN/Writing_guidelines/Attrib_copyright_license">a Creative Commons license</a>.</p></div></div></footer></div><script type="application/json" id="hydration">{"url":"/en-US/docs/Web/API/RequestInit","doc":{"isMarkdown":true,"isTranslated":false,"isActive":true,"flaws":{},"title":"RequestInit","mdn_url":"/en-US/docs/Web/API/RequestInit","locale":"en-US","native":"English (US)","sidebarHTML":"<ol><li class=\"section\"><a href=\"/en-US/docs/Web/API/Fetch_API\">Fetch API</a></li><li class=\"section\"><em><a href=\"/en-US/docs/Web/API/RequestInit\" aria-current=\"page\"><code>RequestInit</code></a></em></li><li class=\"toggle\"><details open=\"\"><summary>Related pages for Fetch API</summary><ol><li><a href=\"/en-US/docs/Web/API/Headers\"><code>Headers</code></a></li><li><a href=\"/en-US/docs/Web/API/Request\"><code>Request</code></a></li><li><a href=\"/en-US/docs/Web/API/Response\"><code>Response</code></a></li><li><a href=\"/en-US/docs/Web/API/Window/fetch\"><code>Window.fetch()</code></a></li><li><a href=\"/en-US/docs/Web/API/WorkerGlobalScope/fetch\"><code>WorkerGlobalScope.fetch()</code></a></li></ol></details></li></ol>","sidebarMacro":"APIRef","body":[{"type":"prose","value":{"id":null,"title":null,"isH3":false,"content":"<p>The <strong><code>RequestInit</code></strong> dictionary of the <a href=\"/en-US/docs/Web/API/Fetch_API\">Fetch API</a> represents the set of options that can be used to configure a Fetch request.</p>\n<p>You can pass a <code>RequestInit</code> object into the <a href=\"/en-US/docs/Web/API/Request/Request\" title=\"Request()\"><code>Request()</code></a> constructor, or directly into the <a href=\"/en-US/docs/Web/API/Window/fetch\"><code>fetch()</code></a> function call.</p>\n<p>You can also construct a <code>Request</code> with a <code>RequestInit</code>, and pass the <code>Request</code> to a <code>fetch()</code> call along with another <code>RequestInit</code>. If you do this, and the same option is set in both places, then the value passed directly into <code>fetch()</code> is used.</p>"}},{"type":"prose","value":{"id":"instance_properties","title":"Instance properties","isH3":false,"content":"<dl>\n <dt id=\"attributionreporting\"><a href=\"#attributionreporting\"><code>attributionReporting</code></a> <span class=\"badge inline optional\">Optional</span> <abbr class=\"icon icon-experimental\" title=\"Experimental. Expect behavior to change in the future.\">\n <span class=\"visually-hidden\">Experimental</span>\n</abbr></dt>\n <dd>\n <p>Indicates that you want the request's response to be able to register a JavaScript-based <a href=\"/en-US/docs/Web/API/Attribution_Reporting_API/Registering_sources#javascript-based_event_sources\">attribution source</a> or <a href=\"/en-US/docs/Web/API/Attribution_Reporting_API/Registering_triggers#javascript-based_attribution_triggers\">attribution trigger</a>. <code>attributionReporting</code> is an object containing the following properties:</p>\n <dl>\n <dt id=\"eventsourceeligible\"><a href=\"#eventsourceeligible\"><code>eventSourceEligible</code></a></dt>\n <dd>\n <p>A boolean. If set to <code>true</code>, the request's response is eligible to register an attribution source. If set to <code>false</code>, it isn't.</p>\n </dd>\n <dt id=\"triggereligible\"><a href=\"#triggereligible\"><code>triggerEligible</code></a></dt>\n <dd>\n <p>A boolean. If set to <code>true</code>, the request's response is eligible to register an attribution trigger. If set to <code>false</code>, it isn't.</p>\n </dd>\n </dl>\n <p>See the <a href=\"/en-US/docs/Web/API/Attribution_Reporting_API\">Attribution Reporting API</a> for more details.</p>\n </dd>\n <dt id=\"body\"><a href=\"#body\"><code>body</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>The request body contains content to send to the server, for example in a <a href=\"/en-US/docs/Web/HTTP/Methods/POST\"><code>POST</code></a> or <a href=\"/en-US/docs/Web/HTTP/Methods/PUT\"><code>PUT</code></a> request. It is specified as an instance of any of the following types:</p>\n <ul>\n <li>a string</li>\n <li><a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/ArrayBuffer\"><code>ArrayBuffer</code></a></li>\n <li><a href=\"/en-US/docs/Web/API/Blob\"><code>Blob</code></a></li>\n <li><a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/DataView\"><code>DataView</code></a></li>\n <li><a href=\"/en-US/docs/Web/API/File\"><code>File</code></a></li>\n <li><a href=\"/en-US/docs/Web/API/FormData\"><code>FormData</code></a></li>\n <li><a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray\"><code>TypedArray</code></a></li>\n <li><a href=\"/en-US/docs/Web/API/URLSearchParams\"><code>URLSearchParams</code></a></li>\n <li><a href=\"/en-US/docs/Web/API/ReadableStream\"><code>ReadableStream</code></a></li>\n </ul>\n <p>See <a href=\"/en-US/docs/Web/API/Fetch_API/Using_Fetch#setting_a_body\">Setting a body</a> for more details.</p>\n </dd>\n <dt id=\"browsingtopics\"><a href=\"#browsingtopics\"><code>browsingTopics</code></a> <span class=\"badge inline optional\">Optional</span> <abbr class=\"icon icon-experimental\" title=\"Experimental. Expect behavior to change in the future.\">\n <span class=\"visually-hidden\">Experimental</span>\n</abbr></dt>\n <dd>\n <p>A boolean specifying that the selected topics for the current user should be sent in a <a href=\"/en-US/docs/Web/HTTP/Headers/Sec-Browsing-Topics\"><code>Sec-Browsing-Topics</code></a> header with the associated request.</p>\n <p>See <a href=\"/en-US/docs/Web/API/Topics_API/Using\">Using the Topics API</a> for more details.</p>\n </dd>\n <dt id=\"cache\"><a href=\"#cache\"><code>cache</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>The <a href=\"/en-US/docs/Web/API/Request/cache\">cache mode</a> you want to use for the request. This may be any one of the following values:</p>\n <dl>\n <dt id=\"default\"><a href=\"#default\"><code>default</code></a></dt>\n <dd>\n <p>The browser looks in its HTTP cache for a response matching the request.</p>\n <ul>\n <li>If there is a match and it is <a href=\"/en-US/docs/Web/HTTP/Caching#fresh_and_stale_based_on_age\">fresh</a>, it will be returned from the cache.</li>\n <li>If there is a match but it is <a href=\"/en-US/docs/Web/HTTP/Caching#fresh_and_stale_based_on_age\">stale</a>, the browser will make a <a href=\"/en-US/docs/Web/HTTP/Conditional_requests\">conditional request</a> to the remote server. If the server indicates that the resource has not changed, it will be returned from the cache. Otherwise the resource will be downloaded from the server and the cache will be updated.</li>\n <li>If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.</li>\n </ul>\n </dd>\n <dt id=\"no-store\"><a href=\"#no-store\"><code>no-store</code></a></dt>\n <dd>\n <p>The browser fetches the resource from the remote server without first looking in the cache, <em>and will not</em> update the cache with the downloaded resource.</p>\n </dd>\n <dt id=\"reload\"><a href=\"#reload\"><code>reload</code></a></dt>\n <dd>\n <p>The browser fetches the resource from the remote server without first looking in the cache, <em>but then will</em> update the cache with the downloaded resource.</p>\n </dd>\n <dt id=\"no-cache\"><a href=\"#no-cache\"><code>no-cache</code></a></dt>\n <dd>\n <p>The browser looks in its HTTP cache for a response matching the request.</p>\n <ul>\n <li>If there is a match, <em>fresh or stale,</em> the browser will make a <a href=\"/en-US/docs/Web/HTTP/Conditional_requests\">conditional request</a> to the remote server. If the server indicates that the resource has not changed, it will be returned from the cache. Otherwise the resource will be downloaded from the server and the cache will be updated.</li>\n <li>If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.</li>\n </ul>\n </dd>\n <dt id=\"force-cache\"><a href=\"#force-cache\"><code>force-cache</code></a></dt>\n <dd>\n <p>The browser looks in its HTTP cache for a response matching the request.</p>\n <ul>\n <li>If there is a match, <em>fresh or stale</em>, it will be returned from the cache.</li>\n <li>If there is no match, the browser will make a normal request, and will update the cache with the downloaded resource.</li>\n </ul>\n </dd>\n <dt id=\"only-if-cached\"><a href=\"#only-if-cached\"><code>only-if-cached</code></a></dt>\n <dd>\n <p>The browser looks in its HTTP cache for a response matching the request. <abbr class=\"icon icon-experimental\" title=\"Experimental. Expect behavior to change in the future.\">\n <span class=\"visually-hidden\">Experimental</span>\n</abbr></p>\n <ul>\n <li>If there is a match, <em>fresh or stale</em>, it will be returned from the cache.</li>\n <li>If there is no match, a network error is returned.</li>\n </ul>\n </dd>\n </dl>\n <p>The <code>\"only-if-cached\"</code> mode can only be used if the request's <a href=\"/en-US/docs/Web/API/Request/mode\"><code>mode</code></a> is <code>\"same-origin\"</code>. Cached redirects will be followed if the request's <code>redirect</code> property is <code>\"follow\"</code> and the redirects do not violate the <code>\"same-origin\"</code> mode.</p>\n </dd>\n <dt id=\"credentials\"><a href=\"#credentials\"><code>credentials</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>Controls whether or not the browser sends credentials with the request, as well as whether any <strong><code>Set-Cookie</code></strong> response headers are respected. Credentials are cookies, <a href=\"/en-US/docs/Glossary/TLS\">TLS</a> client certificates, or authentication headers containing a username and password. This option may be any one of the following values:</p>\n <dl>\n <dt id=\"omit\"><a href=\"#omit\"><code>omit</code></a></dt>\n <dd>\n <p>Never send credentials in the request or include credentials in the response.</p>\n </dd>\n <dt id=\"same-origin\"><a href=\"#same-origin\"><code>same-origin</code></a></dt>\n <dd>\n <p>Only send and include credentials for same-origin requests.</p>\n </dd>\n <dt id=\"include\"><a href=\"#include\"><code>include</code></a></dt>\n <dd>\n <p>Always include credentials, even for cross-origin requests.</p>\n </dd>\n </dl>\n <p>Including credentials in cross-origin requests can make a site vulnerable to <a href=\"/en-US/docs/Glossary/CSRF\">CSRF</a> attacks, so even if <code>credentials</code> is set to <code>include</code>, the server must also agree to their inclusion by including the <a href=\"/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Credentials\"><code>Access-Control-Allow-Credentials</code></a> in its response. Additionally, in this situation the server must explicitly specify the client's origin in the <a href=\"/en-US/docs/Web/HTTP/Headers/Access-Control-Allow-Origin\"><code>Access-Control-Allow-Origin</code></a> response header (that is, <code>*</code> is not allowed).</p>\n <p>See <a href=\"/en-US/docs/Web/API/Fetch_API/Using_Fetch#including_credentials\">Including credentials</a> for more details.</p>\n <p>Defaults to <code>same-origin</code>.</p>\n </dd>\n <dt id=\"headers\"><a href=\"#headers\"><code>headers</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>\n Any headers you want to add to your request, contained\n within a <a href=\"/en-US/docs/Web/API/Headers\"><code>Headers</code></a> object or an object literal whose keys are the names of headers and whose values are the header values.\n </p>\n <p>Many headers are set automatically by the browser and can't be set by a script: these are called <a href=\"/en-US/docs/Glossary/Forbidden_header_name\">Forbidden header names</a>.</p>\n <p>If the <code>mode</code> option is set to <code>no-cors</code>, you can only set <a href=\"/en-US/docs/Glossary/CORS-safelisted_request_header\">CORS-safelisted request headers</a>.</p>\n <p>See <a href=\"/en-US/docs/Web/API/Fetch_API/Using_Fetch#setting_headers\">Setting headers</a> for more details.</p>\n </dd>\n <dt id=\"integrity\"><a href=\"#integrity\"><code>integrity</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>\n Contains the <a href=\"/en-US/docs/Web/Security/Subresource_Integrity\">subresource integrity</a>\n value of the request.\n </p>\n <p>This will be checked when the resource is fetched, just as it would be when the <a href=\"/en-US/docs/Web/HTML/Element/script#integrity\"><code>integrity</code></a> attribute is set on a <a href=\"/en-US/docs/Web/HTML/Element/script\"><code><script></code></a> element. The browser will compute the <a href=\"/en-US/docs/Glossary/Cryptographic_hash_function\">hash</a> of the fetched resource using the specified algorithm, and if the result does not match the value specified, the browser will reject the fetch request with a network error.</p>\n <p>The format of this option is <code><hash-algo>-<hash-source></code> where:</p>\n <ul>\n <li><code><hash-algo></code> is one of the following values: <code>sha256</code>, <code>sha384</code>, or <code>sha512</code></li>\n <li><code><hash-source></code> is the <a href=\"/en-US/docs/Glossary/Base64\">Base64-encoding</a> of the result of hashing the resource with the specified hash algorithm.</li>\n </ul>\n <p>Defaults to an empty string.</p>\n </dd>\n <dt id=\"keepalive\"><a href=\"#keepalive\"><code>keepalive</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>A boolean. When set to <code>true</code>, the browser will not abort the associated request if the page that initiated it is unloaded before the request is complete. This enables a <a href=\"/en-US/docs/Web/API/Window/fetch\" title=\"fetch()\"><code>fetch()</code></a> request to function as an alternative to <a href=\"/en-US/docs/Web/API/Navigator/sendBeacon\"><code>Navigator.sendBeacon()</code></a> when sending analytics at the end of a session, which has some advantages (you can use HTTP methods other than <a href=\"/en-US/docs/Web/HTTP/Methods/POST\"><code>POST</code></a>, customize request properties, and access the server response via the fetch <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise\"><code>Promise</code></a> fulfillment). It is also available in <a href=\"/en-US/docs/Web/API/Service_Worker_API\">service workers</a>.</p>\n <p>The body size for <code>keepalive</code> requests is limited to 64 kibibytes.</p>\n <p>Defaults to <code>false</code>.</p>\n </dd>\n <dt id=\"method\"><a href=\"#method\"><code>method</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>The <a href=\"/en-US/docs/Web/HTTP/Methods\">request method</a>.</p>\n <p>Defaults to <a href=\"/en-US/docs/Web/HTTP/Methods/GET\"><code>GET</code></a>.</p>\n </dd>\n <dt id=\"mode\"><a href=\"#mode\"><code>mode</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>Sets cross-origin behavior for the request. One of the following values:</p>\n <dl>\n <dt id=\"same-origin_2\"><a href=\"#same-origin_2\"><code>same-origin</code></a></dt>\n <dd>\n <p>Disallows cross-origin requests. If a <code>same-origin</code> request is sent to a different origin, the result is a network error.</p>\n </dd>\n <dt id=\"cors\"><a href=\"#cors\"><code>cors</code></a></dt>\n <dd>\n <p>If the request is cross-origin then it will use the <a href=\"/en-US/docs/Web/HTTP/CORS\">Cross-Origin Resource Sharing (CORS)</a> mechanism. Only <a href=\"/en-US/docs/Glossary/CORS-safelisted_response_header\">CORS-safelisted response headers</a> are exposed in the response.</p>\n </dd>\n <dt id=\"no-cors\"><a href=\"#no-cors\"><code>no-cors</code></a></dt>\n <dd>\n <p>Disables CORS for cross-origin requests. This option comes with the following restrictions:</p>\n <ul>\n <li>The method may only be one of <code>HEAD</code>, <code>GET</code> or <code>POST</code>.</li>\n <li>The headers may only be <a href=\"/en-US/docs/Glossary/CORS-safelisted_request_header\">CORS-safelisted request headers</a>, with the additional restriction that the <a href=\"/en-US/docs/Web/HTTP/Headers/Range\"><code>Range</code></a> header is also not allowed. This also applies to any headers added by service workers.</li>\n <li>The response is <em>opaque</em>, meaning that its headers and body are not available to JavaScript, and its <a href=\"/en-US/docs/Web/API/Response/status\" title=\"status code\">status code</a> is always <code>0</code>.</li>\n </ul>\n <p>The main application for <code>no-cors</code> is for a service worker: although the response to a <code>no-cors</code> request can't be read by JavaScript, it can be cached by a service worker and then used as a response to an intercepted fetch request. Note that in this situation you don't know whether the request succeeded or not, so you should adopt a caching strategy which enables the cached response to be updated from the network (such as <a href=\"/en-US/docs/Web/Progressive_web_apps/Guides/Caching#cache_first_with_cache_refresh\">cache first with cache refresh</a>).</p>\n </dd>\n <dt id=\"navigate\"><a href=\"#navigate\"><code>navigate</code></a></dt>\n <dd>\n <p>Used only by HTML navigation. A <code>navigate</code> request is created only while navigating between documents.</p>\n </dd>\n </dl>\n <p>See <a href=\"/en-US/docs/Web/API/Fetch_API/Using_Fetch#making_cross-origin_requests\">Making cross-origin requests</a> for more details.</p>\n <p>Defaults to <code>cors</code>.</p>\n </dd>\n <dt id=\"priority\"><a href=\"#priority\"><code>priority</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>Specifies the priority of the fetch request relative to other requests of the same type. Must be one of the following:</p>\n <dl>\n <dt id=\"high\"><a href=\"#high\"><code>high</code></a></dt>\n <dd>\n <p>A high priority fetch request relative to other requests of the same type.</p>\n </dd>\n <dt id=\"low\"><a href=\"#low\"><code>low</code></a></dt>\n <dd>\n <p>A low priority fetch request relative to other requests of the same type.</p>\n </dd>\n <dt id=\"auto\"><a href=\"#auto\"><code>auto</code></a></dt>\n <dd>\n <p>\n No user preference for the fetch priority.\n It is used if no value is set or if an invalid value is set.\n </p>\n </dd>\n </dl>\n <p>Defaults to <code>auto</code>.</p>\n </dd>\n <dt id=\"redirect\"><a href=\"#redirect\"><code>redirect</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>Determines the browser's behavior in case the server replies with a <a href=\"/en-US/docs/Web/HTTP/Status#redirection_messages\">redirect status</a>. One of the following values:</p>\n <dl>\n <dt id=\"follow\"><a href=\"#follow\"><code>follow</code></a></dt>\n <dd>\n <p>Automatically follow redirects.</p>\n </dd>\n <dt id=\"error\"><a href=\"#error\"><code>error</code></a></dt>\n <dd>\n <p>Reject the promise with a network error when a redirect status is returned.</p>\n </dd>\n <dt id=\"manual\"><a href=\"#manual\"><code>manual</code></a></dt>\n <dd>\n <p>Return a response with almost all fields filtered out, to enable a service worker to store the response and later replay it.</p>\n </dd>\n </dl>\n <p>Defaults to <code>follow</code>.</p>\n </dd>\n <dt id=\"referrer\"><a href=\"#referrer\"><code>referrer</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>A string specifying the value to use for the request's <a href=\"/en-US/docs/Web/HTTP/Headers/Referer\"><code>Referer</code></a> header. One of the following:</p>\n <dl>\n <dt id=\"a_same-origin_relative_or_absolute_url\"><a href=\"#a_same-origin_relative_or_absolute_url\">A same-origin relative or absolute URL</a></dt>\n <dd>\n <p>Set the <code>Referer</code> header to the given value. Relative URLs are resolved relative to the URL of the page that made the request.</p>\n </dd>\n <dt id=\"an_empty_string\"><a href=\"#an_empty_string\">An empty string</a></dt>\n <dd>\n <p>Omit the <code>Referer</code> header.</p>\n </dd>\n <dt id=\"aboutclient\"><a href=\"#aboutclient\"><code>about:client</code></a></dt>\n <dd>\n <p>Set the <code>Referer</code> header to the default value for the context of the request (for example, the URL of the page that made the request).</p>\n </dd>\n </dl>\n <p>Defaults to <code>about:client</code>.</p>\n </dd>\n <dt id=\"referrerpolicy\"><a href=\"#referrerpolicy\"><code>referrerPolicy</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>A string that sets a policy for the <a href=\"/en-US/docs/Web/HTTP/Headers/Referer\"><code>Referer</code></a> header. The syntax and semantics of this option are exactly the same as for the <a href=\"/en-US/docs/Web/HTTP/Headers/Referrer-Policy\"><code>Referrer-Policy</code></a> header.</p>\n </dd>\n <dt id=\"signal\"><a href=\"#signal\"><code>signal</code></a> <span class=\"badge inline optional\">Optional</span></dt>\n <dd>\n <p>An <a href=\"/en-US/docs/Web/API/AbortSignal\"><code>AbortSignal</code></a>. If this option is set, the request can be canceled by calling <a href=\"/en-US/docs/Web/API/AbortController/abort\" title=\"abort()\"><code>abort()</code></a> on the corresponding <code>AbortController</code>.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"examples","title":"Examples","isH3":false,"content":""}},{"type":"prose","value":{"id":"passing_options_into_fetch","title":"Passing options into <code>fetch()</code>","isH3":true,"content":"<p>In this example we pass the <code>method</code>, <code>body</code>, and <code>headers</code> options directly into the <a href=\"/en-US/docs/Web/API/Window/fetch\"><code>fetch()</code></a> method call:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>async function post() {\n const response = await fetch(\"https://example.org/post\", {\n method: \"POST\",\n body: JSON.stringify({ username: \"example\" }),\n headers: {\n \"Content-Type\": \"application/json\",\n },\n });\n\n console.log(response.status);\n}\n</code></pre></div>"}},{"type":"prose","value":{"id":"passing_options_into_the_request_constructor","title":"Passing options into the <code>Request()</code> constructor","isH3":true,"content":"<p>In this example we create a <a href=\"/en-US/docs/Web/API/Request\"><code>Request</code></a>, passing the same set of options into its constructor, and then pass the request into <code>fetch()</code>:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>async function post() {\n const request = new Request(\"https://example.org/post\", {\n method: \"POST\",\n body: JSON.stringify({ username: \"example\" }),\n headers: {\n \"Content-Type\": \"application/json\",\n },\n });\n\n const response = await fetch(request);\n\n console.log(response.status);\n}\n</code></pre></div>"}},{"type":"prose","value":{"id":"passing_options_into_both_request_and_fetch","title":"Passing options into both <code>Request()</code> and <code>fetch()</code>","isH3":true,"content":"<p>In this example we create a <a href=\"/en-US/docs/Web/API/Request\"><code>Request</code></a>, passing the <code>method</code>, <code>headers</code>, and <code>body</code> options into its constructor. We then pass the request into <code>fetch()</code> along with <code>body</code> and <code>referrer</code> options:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>async function post() {\n const request = new Request(\"https://example.org/post\", {\n method: \"POST\",\n headers: {\n \"Content-Type\": \"application/json\",\n },\n body: JSON.stringify({ username: \"example1\" }),\n });\n\n const response = await fetch(request, {\n body: JSON.stringify({ username: \"example2\" }),\n referrer: \"\",\n });\n\n console.log(response.status);\n}\n</code></pre></div>\n<p>In this case the request will be sent with the following options:</p>\n<ul>\n <li><code>method: \"POST\"</code></li>\n <li><code>headers: {\"Content-Type\": \"application/json\"}</code></li>\n <li><code>body: '{\"username\":\"example2\"}'</code></li>\n <li><code>referrer: \"\"</code></li>\n</ul>"}},{"type":"specifications","value":{"title":"Specifications","id":"specifications","isH3":false,"specifications":[{"bcdSpecificationURL":"https://fetch.spec.whatwg.org/#requestinit","title":"Fetch Standard"}],"query":"undefined"}},{"type":"prose","value":{"id":"see_also","title":"See also","isH3":false,"content":"<ul>\n <li><a href=\"/en-US/docs/Web/API/Fetch_API/Using_Fetch\">Using Fetch</a></li>\n <li><a href=\"/en-US/docs/Web/API/Service_Worker_API\">ServiceWorker API</a></li>\n <li><a href=\"/en-US/docs/Web/HTTP/CORS\">HTTP access control (CORS)</a></li>\n <li><a href=\"/en-US/docs/Web/HTTP\">HTTP</a></li>\n</ul>"}}],"toc":[{"text":"Instance properties","id":"instance_properties"},{"text":"Examples","id":"examples"},{"text":"Specifications","id":"specifications"},{"text":"See also","id":"see_also"}],"summary":"The RequestInit dictionary of the Fetch API represents the set of options that can be used to configure a Fetch request.","popularity":0,"modified":"2024-10-31T04:58:07.000Z","other_translations":[{"locale":"de","title":"RequestInit","native":"Deutsch"},{"locale":"ja","title":"RequestInit","native":"日本語"}],"pageType":"web-api-interface","source":{"folder":"en-us/web/api/requestinit","github_url":"https://github.com/mdn/content/blob/main/files/en-us/web/api/requestinit/index.md","last_commit_url":"https://github.com/mdn/content/commit/22526bdf0076aec093ba0a1ba32a6bb0d4ffd853","filename":"index.md"},"short_title":"RequestInit","parents":[{"uri":"/en-US/docs/Web","title":"References"},{"uri":"/en-US/docs/Web/API","title":"Web APIs"},{"uri":"/en-US/docs/Web/API/RequestInit","title":"RequestInit"}],"pageTitle":"RequestInit - Web APIs | MDN","noIndexing":false}}</script></body></html>