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>ReadableStream - Web APIs | MDN</title><link rel="alternate" title="ReadableStream" href="https://developer.mozilla.org/de/docs/Web/API/ReadableStream" hrefLang="de"/><link rel="alternate" title="ReadableStream" href="https://developer.mozilla.org/ja/docs/Web/API/ReadableStream" hrefLang="ja"/><link rel="alternate" title="ReadableStream" href="https://developer.mozilla.org/ko/docs/Web/API/ReadableStream" hrefLang="ko"/><link rel="alternate" title="ReadableStream" href="https://developer.mozilla.org/zh-CN/docs/Web/API/ReadableStream" hrefLang="zh"/><link rel="alternate" title="ReadableStream" href="https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream" 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 ReadableStream interface, including its constructor, properties, and methods, code examples, specifications, and browser compatibility."/><meta property="og:url" content="https://developer.mozilla.org/en-US/docs/Web/API/ReadableStream"/><meta property="og:title" content="ReadableStream - Web APIs | MDN"/><meta property="og:type" content="website"/><meta property="og:locale" content="en_US"/><meta property="og:description" content="The ReadableStream interface of the Streams API represents a readable stream of byte data. The Fetch API offers a concrete instance of a ReadableStream through the body property of a Response object."/><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/ReadableStream"/><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.9722bf44.js"></script><link href="/static/css/main.27d5b2a8.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%2FReadableStream" class="login-link" rel="nofollow">Log in</a></li><li><a href="/users/fxa/login/authenticate/?next=%2Fen-US%2Fdocs%2FWeb%2FAPI%2FReadableStream" 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/ReadableStream" class="breadcrumb-current-page" property="item" typeof="WebPage"><span property="name">ReadableStream</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/ReadableStream" 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/ReadableStream" class="button submenu-item"><span>日本語</span></a></li><li class=" "><a data-locale="ko" href="/ko/docs/Web/API/ReadableStream" class="button submenu-item"><span>한국어</span></a></li><li class=" "><a data-locale="zh-CN" href="/zh-CN/docs/Web/API/ReadableStream" class="button submenu-item"><span>中文 (简体)</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="#constructor">Constructor</a></li><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="#static_methods">Static methods</a></li><li class="document-toc-item "><a class="document-toc-link" href="#instance_methods">Instance methods</a></li><li class="document-toc-item "><a class="document-toc-link" href="#async_iteration">Async iteration</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="#browser_compatibility">Browser compatibility</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/Streams_API">Streams API</a></li><li class="section"><em><a href="/en-US/docs/Web/API/ReadableStream" aria-current="page"><code>ReadableStream</code></a></em></li><li class="toggle"><details open=""><summary>Constructor</summary><ol><li><a href="/en-US/docs/Web/API/ReadableStream/ReadableStream"><code>ReadableStream()</code></a></li></ol></details></li><li class="toggle"><details open=""><summary>Instance properties</summary><ol><li><a href="/en-US/docs/Web/API/ReadableStream/locked"><code>locked</code></a></li></ol></details></li><li class="toggle"><details open=""><summary>Static methods</summary><ol><li><a href="/en-US/docs/Web/API/ReadableStream/from_static"><code>from()</code></a><abbr class="icon icon-experimental" title="Experimental. Expect behavior to change in the future."> <span class="visually-hidden">Experimental</span> </abbr></li></ol></details></li><li class="toggle"><details open=""><summary>Instance methods</summary><ol><li><a href="/en-US/docs/Web/API/ReadableStream/cancel"><code>cancel()</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStream/getReader"><code>getReader()</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStream/pipeThrough"><code>pipeThrough()</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStream/pipeTo"><code>pipeTo()</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStream/tee"><code>tee()</code></a></li></ol></details></li><li class="toggle"><details open=""><summary>Related pages for Streams</summary><ol><li><a href="/en-US/docs/Web/API/ByteLengthQueuingStrategy"><code>ByteLengthQueuingStrategy</code></a></li><li><a href="/en-US/docs/Web/API/CountQueuingStrategy"><code>CountQueuingStrategy</code></a></li><li><a href="/en-US/docs/Web/API/ReadableByteStreamController"><code>ReadableByteStreamController</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStreamBYOBReader"><code>ReadableStreamBYOBReader</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStreamBYOBRequest"><code>ReadableStreamBYOBRequest</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStreamDefaultController"><code>ReadableStreamDefaultController</code></a></li><li><a href="/en-US/docs/Web/API/ReadableStreamDefaultReader"><code>ReadableStreamDefaultReader</code></a></li><li><a href="/en-US/docs/Web/API/Response/body"><code>Response.body</code></a></li><li><a href="/en-US/docs/Web/API/TransformStream"><code>TransformStream</code></a></li><li><a href="/en-US/docs/Web/API/TransformStreamDefaultController"><code>TransformStreamDefaultController</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/WritableStream"><code>WritableStream</code></a></li><li><a href="/en-US/docs/Web/API/WritableStreamDefaultController"><code>WritableStreamDefaultController</code></a></li><li><a href="/en-US/docs/Web/API/WritableStreamDefaultWriter"><code>WritableStreamDefaultWriter</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="#constructor">Constructor</a></li><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="#static_methods">Static methods</a></li><li class="document-toc-item "><a class="document-toc-link" href="#instance_methods">Instance methods</a></li><li class="document-toc-item "><a class="document-toc-link" href="#async_iteration">Async iteration</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="#browser_compatibility">Browser compatibility</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>ReadableStream</h1></header><div class="section-content"><div class="notecard note"> <p><strong>Note:</strong> This feature is available in <a href="/en-US/docs/Web/API/Web_Workers_API">Web Workers</a>.</p> </div> <p>The <code>ReadableStream</code> interface of the <a href="/en-US/docs/Web/API/Streams_API">Streams API</a> represents a readable stream of byte data. The <a href="/en-US/docs/Web/API/Fetch_API">Fetch API</a> offers a concrete instance of a <code>ReadableStream</code> through the <a href="/en-US/docs/Web/API/Response/body" title="body"><code>body</code></a> property of a <a href="/en-US/docs/Web/API/Response"><code>Response</code></a> object.</p> <p><code>ReadableStream</code> is a <a href="/en-US/docs/Web/API/Web_Workers_API/Transferable_objects">transferable object</a>.</p></div><section aria-labelledby="constructor"><h2 id="constructor"><a href="#constructor">Constructor</a></h2><div class="section-content"><dl> <dt id="readablestream"><a href="/en-US/docs/Web/API/ReadableStream/ReadableStream" title="ReadableStream()"><code>ReadableStream()</code></a></dt> <dd> <p>Creates and returns a readable stream object from the given handlers.</p> </dd> </dl></div></section><section aria-labelledby="instance_properties"><h2 id="instance_properties"><a href="#instance_properties">Instance properties</a></h2><div class="section-content"><dl> <dt id="readablestream.locked"><a href="/en-US/docs/Web/API/ReadableStream/locked"><code>ReadableStream.locked</code></a> <span class="badge inline readonly" title="This value may not be changed.">Read only </span></dt> <dd> <p>Returns a boolean indicating whether or not the readable stream is locked to a reader.</p> </dd> </dl></div></section><section aria-labelledby="static_methods"><h2 id="static_methods"><a href="#static_methods">Static methods</a></h2><div class="section-content"><dl> <dt id="readablestream.from"><a href="/en-US/docs/Web/API/ReadableStream/from_static" title="ReadableStream.from()"><code>ReadableStream.from()</code></a> <abbr class="icon icon-experimental" title="Experimental. Expect behavior to change in the future."> <span class="visually-hidden">Experimental</span> </abbr></dt> <dd> <p>Returns <code>ReadableStream</code> from a provided iterable or async iterable object, such as an array, a set, an async generator, and so on.</p> </dd> </dl></div></section><section aria-labelledby="instance_methods"><h2 id="instance_methods"><a href="#instance_methods">Instance methods</a></h2><div class="section-content"><dl> <dt id="readablestream.cancel"><a href="/en-US/docs/Web/API/ReadableStream/cancel"><code>ReadableStream.cancel()</code></a></dt> <dd> <p>Returns a <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise"><code>Promise</code></a> that resolves when the stream is canceled. Calling this method signals a loss of interest in the stream by a consumer. The supplied <code>reason</code> argument will be given to the underlying source, which may or may not use it.</p> </dd> <dt id="readablestream.getreader"><a href="/en-US/docs/Web/API/ReadableStream/getReader"><code>ReadableStream.getReader()</code></a></dt> <dd> <p>Creates a reader and locks the stream to it. While the stream is locked, no other reader can be acquired until this one is released.</p> </dd> <dt id="readablestream.pipethrough"><a href="/en-US/docs/Web/API/ReadableStream/pipeThrough"><code>ReadableStream.pipeThrough()</code></a></dt> <dd> <p>Provides a chainable way of piping the current stream through a transform stream or any other writable/readable pair.</p> </dd> <dt id="readablestream.pipeto"><a href="/en-US/docs/Web/API/ReadableStream/pipeTo"><code>ReadableStream.pipeTo()</code></a></dt> <dd> <p>Pipes the current ReadableStream to a given <a href="/en-US/docs/Web/API/WritableStream"><code>WritableStream</code></a> and returns a <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise"><code>Promise</code></a> that fulfills when the piping process completes successfully, or rejects if any errors were encountered.</p> </dd> <dt id="readablestream.tee"><a href="/en-US/docs/Web/API/ReadableStream/tee"><code>ReadableStream.tee()</code></a></dt> <dd> <p>The <code>tee</code> method <a href="https://streams.spec.whatwg.org/#tee-a-readable-stream" class="external" target="_blank">tees</a> this readable stream, returning a two-element array containing the two resulting branches as new <code>ReadableStream</code> instances. Each of those streams receives the same incoming data.</p> </dd> </dl></div></section><section aria-labelledby="async_iteration"><h2 id="async_iteration"><a href="#async_iteration">Async iteration</a></h2><div class="section-content"><p> <code>ReadableStream</code> implements the <a href="/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_async_iterator_and_async_iterable_protocols">async iterable protocol</a>. This enables asynchronous iteration over the chunks in a stream using the <a href="/en-US/docs/Web/JavaScript/Reference/Statements/for-await...of"><code>for await...of</code></a> syntax: </p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>const stream = new ReadableStream(getSomeSource()); for await (const chunk of stream) { // Do something with each 'chunk' } </code></pre></div> <p> The async iterator consumes the stream until it runs out of data or otherwise terminates. The loop can also exit early due to a <code>break</code>, <code>throw</code>, or <code>return</code> statement. </p> <p> While iterating, the stream is locked to prevent other consumers from acquiring a reader (attempting to iterate over a stream that is already locked will throw a <code>TypeError</code>). This lock is released when the loop exits. </p> <p> By default, exiting the loop will also cancel the stream, so that it can no longer be used. To continue to use a stream after exiting the loop, pass <code>{ preventCancel: true }</code> to the stream's <code>values()</code> method: </p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>for await (const chunk of stream.values({ preventCancel: true })) { // Do something with 'chunk' break; } // Acquire a reader for the stream and continue reading ... </code></pre></div></div></section><section aria-labelledby="examples"><h2 id="examples"><a href="#examples">Examples</a></h2><div class="section-content"></div></section><section aria-labelledby="fetch_stream"><h3 id="fetch_stream"><a href="#fetch_stream">Fetch stream</a></h3><div class="section-content"><p>In the following example, an artificial <a href="/en-US/docs/Web/API/Response"><code>Response</code></a> is created to stream HTML fragments fetched from another resource to the browser.</p> <p>It demonstrates the usage of a <code>ReadableStream</code> in combination with a <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array"><code>Uint8Array</code></a>.</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>fetch("https://www.example.org") .then((response) => response.body) .then((rb) => { const reader = rb.getReader(); return new ReadableStream({ start(controller) { // The following function handles each data chunk function push() { // "done" is a Boolean and value a "Uint8Array" reader.read().then(({ done, value }) => { // If there is no more data to read if (done) { console.log("done", done); controller.close(); return; } // Get the data and send it to the browser via the controller controller.enqueue(value); // Check chunks by logging to the console console.log(done, value); push(); }); } push(); }, }); }) .then((stream) => // Respond with our stream new Response(stream, { headers: { "Content-Type": "text/html" } }).text(), ) .then((result) => { // Do things with result console.log(result); }); </code></pre></div></div></section><section aria-labelledby="convert_an_iterator_or_async_iterator_to_a_stream"><h3 id="convert_an_iterator_or_async_iterator_to_a_stream"><a href="#convert_an_iterator_or_async_iterator_to_a_stream">Convert an iterator or async iterator to a stream</a></h3><div class="section-content"><p>The <a href="/en-US/docs/Web/API/ReadableStream/from_static" title="from()"><code>from()</code></a> static method can convert an iterator, such as an <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array"><code>Array</code></a> or <a href="/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map"><code>Map</code></a>, or an <a href="/en-US/docs/Web/JavaScript/Guide/Iterators_and_generators">(async) iterator</a> to a readable stream:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>const myReadableStream = ReadableStream.from(iteratorOrAsyncIterator); </code></pre></div> <p>On browsers that don't support the <code>from()</code> method you can instead create your own <a href="/en-US/docs/Web/API/Streams_API/Using_readable_streams#creating_your_own_custom_readable_stream">custom readable stream</a> to achieve the same result:</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>function iteratorToStream(iterator) { return new ReadableStream({ async pull(controller) { const { value, done } = await iterator.next(); if (value) { controller.enqueue(value); } if (done) { controller.close(); } }, }); } </code></pre></div> <div class="notecard warning"> <p><strong>Warning:</strong> This example assumes that the return value (<code>value</code> when <code>done</code> is <code>true</code>), if present, is also a chunk to be enqueued. Some iterator APIs may use the return value for different purposes. You may need to adjust the code based on the API you are interacting with.</p> </div></div></section><section aria-labelledby="async_iteration_of_a_stream_using_for_await...of"><h3 id="async_iteration_of_a_stream_using_for_await...of"><a href="#async_iteration_of_a_stream_using_for_await...of">Async iteration of a stream using for await...of</a></h3><div class="section-content"><p>This example shows how you can process the <code>fetch()</code> response using a <a href="/en-US/docs/Web/JavaScript/Reference/Statements/for-await...of"><code>for await...of</code></a> loop to iterate through the arriving chunks.</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>const response = await fetch("https://www.example.org"); let total = 0; // Iterate response.body (a ReadableStream) asynchronously for await (const chunk of response.body) { // Do something with each chunk // Here we just accumulate the size of the response. total += chunk.length; } // Do something with the total console.log(total); </code></pre></div></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://streams.spec.whatwg.org/#rs-class">Streams Standard <br/><small># rs-class</small></a></td></tr></tbody></table><h2 id="browser_compatibility"><a href="#browser_compatibility">Browser compatibility</a></h2><p>BCD tables only load in the browser<noscript> with JavaScript enabled. Enable JavaScript to view data.</noscript></p><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/Streams_API">Streams API concepts</a></li> <li><a href="/en-US/docs/Web/API/Streams_API/Using_readable_streams">Using readable streams</a></li> <li><a href="/en-US/docs/Web/API/Streams_API/Using_readable_byte_streams">Using readable byte stream</a></li> <li><a href="https://whatwg-stream-visualizer.glitch.me/" class="external" target="_blank">WHATWG Stream Visualizer</a>, for a basic visualization of readable, writable, and transform streams.</li> <li><a href="https://github.com/MattiasBuelens/web-streams-polyfill" class="external" target="_blank">Web-streams-polyfill</a> or <a href="https://github.com/stardazed/sd-streams" class="external" target="_blank">sd-streams</a> - polyfills</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="2024-08-30T05:24:07.000Z">Aug 30, 2024</time> by <a href="/en-US/docs/Web/API/ReadableStream/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/readablestream/index.md?plain=1" title="Folder: en-us/web/api/readablestream (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%2FReadableStream&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%2Freadablestream%60%0A*+MDN+URL%3A+https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FAPI%2FReadableStream%0A*+GitHub+URL%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fblob%2Fmain%2Ffiles%2Fen-us%2Fweb%2Fapi%2Freadablestream%2Findex.md%0A*+Last+commit%3A+https%3A%2F%2Fgithub.com%2Fmdn%2Fcontent%2Fcommit%2Fd8c0a74eec7281976ea1a4d13c57fecbed8ab70e%0A*+Document+last+modified%3A+2024-08-30T05%3A24%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/ReadableStream","doc":{"isMarkdown":true,"isTranslated":false,"isActive":true,"flaws":{},"title":"ReadableStream","mdn_url":"/en-US/docs/Web/API/ReadableStream","locale":"en-US","native":"English (US)","browserCompat":["api.ReadableStream"],"sidebarHTML":"<ol><li class=\"section\"><a href=\"/en-US/docs/Web/API/Streams_API\">Streams API</a></li><li class=\"section\"><em><a href=\"/en-US/docs/Web/API/ReadableStream\" aria-current=\"page\"><code>ReadableStream</code></a></em></li><li class=\"toggle\"><details open=\"\"><summary>Constructor</summary><ol><li><a href=\"/en-US/docs/Web/API/ReadableStream/ReadableStream\"><code>ReadableStream()</code></a></li></ol></details></li><li class=\"toggle\"><details open=\"\"><summary>Instance properties</summary><ol><li><a href=\"/en-US/docs/Web/API/ReadableStream/locked\"><code>locked</code></a></li></ol></details></li><li class=\"toggle\"><details open=\"\"><summary>Static methods</summary><ol><li><a href=\"/en-US/docs/Web/API/ReadableStream/from_static\"><code>from()</code></a><abbr class=\"icon icon-experimental\" title=\"Experimental. Expect behavior to change in the future.\">\n <span class=\"visually-hidden\">Experimental</span>\n</abbr></li></ol></details></li><li class=\"toggle\"><details open=\"\"><summary>Instance methods</summary><ol><li><a href=\"/en-US/docs/Web/API/ReadableStream/cancel\"><code>cancel()</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStream/getReader\"><code>getReader()</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStream/pipeThrough\"><code>pipeThrough()</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStream/pipeTo\"><code>pipeTo()</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStream/tee\"><code>tee()</code></a></li></ol></details></li><li class=\"toggle\"><details open=\"\"><summary>Related pages for Streams</summary><ol><li><a href=\"/en-US/docs/Web/API/ByteLengthQueuingStrategy\"><code>ByteLengthQueuingStrategy</code></a></li><li><a href=\"/en-US/docs/Web/API/CountQueuingStrategy\"><code>CountQueuingStrategy</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableByteStreamController\"><code>ReadableByteStreamController</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStreamBYOBReader\"><code>ReadableStreamBYOBReader</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStreamBYOBRequest\"><code>ReadableStreamBYOBRequest</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStreamDefaultController\"><code>ReadableStreamDefaultController</code></a></li><li><a href=\"/en-US/docs/Web/API/ReadableStreamDefaultReader\"><code>ReadableStreamDefaultReader</code></a></li><li><a href=\"/en-US/docs/Web/API/Response/body\"><code>Response.body</code></a></li><li><a href=\"/en-US/docs/Web/API/TransformStream\"><code>TransformStream</code></a></li><li><a href=\"/en-US/docs/Web/API/TransformStreamDefaultController\"><code>TransformStreamDefaultController</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/WritableStream\"><code>WritableStream</code></a></li><li><a href=\"/en-US/docs/Web/API/WritableStreamDefaultController\"><code>WritableStreamDefaultController</code></a></li><li><a href=\"/en-US/docs/Web/API/WritableStreamDefaultWriter\"><code>WritableStreamDefaultWriter</code></a></li></ol></details></li></ol>","sidebarMacro":"APIRef","body":[{"type":"prose","value":{"id":null,"title":null,"isH3":false,"content":"<div class=\"notecard note\">\n <p><strong>Note:</strong> This feature is available in <a href=\"/en-US/docs/Web/API/Web_Workers_API\">Web Workers</a>.</p>\n</div>\n<p>The <code>ReadableStream</code> interface of the <a href=\"/en-US/docs/Web/API/Streams_API\">Streams API</a> represents a readable stream of byte data. The <a href=\"/en-US/docs/Web/API/Fetch_API\">Fetch API</a> offers a concrete instance of a <code>ReadableStream</code> through the <a href=\"/en-US/docs/Web/API/Response/body\" title=\"body\"><code>body</code></a> property of a <a href=\"/en-US/docs/Web/API/Response\"><code>Response</code></a> object.</p>\n<p><code>ReadableStream</code> is a <a href=\"/en-US/docs/Web/API/Web_Workers_API/Transferable_objects\">transferable object</a>.</p>"}},{"type":"prose","value":{"id":"constructor","title":"Constructor","isH3":false,"content":"<dl>\n <dt id=\"readablestream\"><a href=\"/en-US/docs/Web/API/ReadableStream/ReadableStream\" title=\"ReadableStream()\"><code>ReadableStream()</code></a></dt>\n <dd>\n <p>Creates and returns a readable stream object from the given handlers.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"instance_properties","title":"Instance properties","isH3":false,"content":"<dl>\n <dt id=\"readablestream.locked\"><a href=\"/en-US/docs/Web/API/ReadableStream/locked\"><code>ReadableStream.locked</code></a> <span class=\"badge inline readonly\" title=\"This value may not be changed.\">Read only </span></dt>\n <dd>\n <p>Returns a boolean indicating whether or not the readable stream is locked to a reader.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"static_methods","title":"Static methods","isH3":false,"content":"<dl>\n <dt id=\"readablestream.from\"><a href=\"/en-US/docs/Web/API/ReadableStream/from_static\" title=\"ReadableStream.from()\"><code>ReadableStream.from()</code></a> <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>Returns <code>ReadableStream</code> from a provided iterable or async iterable object, such as an array, a set, an async generator, and so on.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"instance_methods","title":"Instance methods","isH3":false,"content":"<dl>\n <dt id=\"readablestream.cancel\"><a href=\"/en-US/docs/Web/API/ReadableStream/cancel\"><code>ReadableStream.cancel()</code></a></dt>\n <dd>\n <p>Returns a <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise\"><code>Promise</code></a> that resolves when the stream is canceled. Calling this method signals a loss of interest in the stream by a consumer. The supplied <code>reason</code> argument will be given to the underlying source, which may or may not use it.</p>\n </dd>\n <dt id=\"readablestream.getreader\"><a href=\"/en-US/docs/Web/API/ReadableStream/getReader\"><code>ReadableStream.getReader()</code></a></dt>\n <dd>\n <p>Creates a reader and locks the stream to it. While the stream is locked, no other reader can be acquired until this one is released.</p>\n </dd>\n <dt id=\"readablestream.pipethrough\"><a href=\"/en-US/docs/Web/API/ReadableStream/pipeThrough\"><code>ReadableStream.pipeThrough()</code></a></dt>\n <dd>\n <p>Provides a chainable way of piping the current stream through a transform stream or any other writable/readable pair.</p>\n </dd>\n <dt id=\"readablestream.pipeto\"><a href=\"/en-US/docs/Web/API/ReadableStream/pipeTo\"><code>ReadableStream.pipeTo()</code></a></dt>\n <dd>\n <p>Pipes the current ReadableStream to a given <a href=\"/en-US/docs/Web/API/WritableStream\"><code>WritableStream</code></a> and returns a <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Promise\"><code>Promise</code></a> that fulfills when the piping process completes successfully, or rejects if any errors were encountered.</p>\n </dd>\n <dt id=\"readablestream.tee\"><a href=\"/en-US/docs/Web/API/ReadableStream/tee\"><code>ReadableStream.tee()</code></a></dt>\n <dd>\n <p>The <code>tee</code> method <a href=\"https://streams.spec.whatwg.org/#tee-a-readable-stream\" class=\"external\" target=\"_blank\">tees</a> this readable stream, returning a two-element array containing the two resulting branches as new <code>ReadableStream</code> instances. Each of those streams receives the same incoming data.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"async_iteration","title":"Async iteration","isH3":false,"content":"<p>\n <code>ReadableStream</code> implements the <a href=\"/en-US/docs/Web/JavaScript/Reference/Iteration_protocols#the_async_iterator_and_async_iterable_protocols\">async iterable protocol</a>.\n This enables asynchronous iteration over the chunks in a stream using the <a href=\"/en-US/docs/Web/JavaScript/Reference/Statements/for-await...of\"><code>for await...of</code></a> syntax:\n</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const stream = new ReadableStream(getSomeSource());\n\nfor await (const chunk of stream) {\n // Do something with each 'chunk'\n}\n</code></pre></div>\n<p>\n The async iterator consumes the stream until it runs out of data or otherwise terminates.\n The loop can also exit early due to a <code>break</code>, <code>throw</code>, or <code>return</code> statement.\n</p>\n<p>\n While iterating, the stream is locked to prevent other consumers from acquiring a reader (attempting to iterate over a stream that is already locked will throw a <code>TypeError</code>).\n This lock is released when the loop exits.\n</p>\n<p>\n By default, exiting the loop will also cancel the stream, so that it can no longer be used.\n To continue to use a stream after exiting the loop, pass <code>{ preventCancel: true }</code> to the stream's <code>values()</code> method:\n</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>for await (const chunk of stream.values({ preventCancel: true })) {\n // Do something with 'chunk'\n break;\n}\n// Acquire a reader for the stream and continue reading ...\n</code></pre></div>"}},{"type":"prose","value":{"id":"examples","title":"Examples","isH3":false,"content":""}},{"type":"prose","value":{"id":"fetch_stream","title":"Fetch stream","isH3":true,"content":"<p>In the following example, an artificial <a href=\"/en-US/docs/Web/API/Response\"><code>Response</code></a> is created to stream HTML fragments fetched from another resource to the browser.</p>\n<p>It demonstrates the usage of a <code>ReadableStream</code> in combination with a <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Uint8Array\"><code>Uint8Array</code></a>.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>fetch(\"https://www.example.org\")\n .then((response) => response.body)\n .then((rb) => {\n const reader = rb.getReader();\n\n return new ReadableStream({\n start(controller) {\n // The following function handles each data chunk\n function push() {\n // \"done\" is a Boolean and value a \"Uint8Array\"\n reader.read().then(({ done, value }) => {\n // If there is no more data to read\n if (done) {\n console.log(\"done\", done);\n controller.close();\n return;\n }\n // Get the data and send it to the browser via the controller\n controller.enqueue(value);\n // Check chunks by logging to the console\n console.log(done, value);\n push();\n });\n }\n\n push();\n },\n });\n })\n .then((stream) =>\n // Respond with our stream\n new Response(stream, { headers: { \"Content-Type\": \"text/html\" } }).text(),\n )\n .then((result) => {\n // Do things with result\n console.log(result);\n });\n</code></pre></div>"}},{"type":"prose","value":{"id":"convert_an_iterator_or_async_iterator_to_a_stream","title":"Convert an iterator or async iterator to a stream","isH3":true,"content":"<p>The <a href=\"/en-US/docs/Web/API/ReadableStream/from_static\" title=\"from()\"><code>from()</code></a> static method can convert an iterator, such as an <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array\"><code>Array</code></a> or <a href=\"/en-US/docs/Web/JavaScript/Reference/Global_Objects/Map\"><code>Map</code></a>, or an <a href=\"/en-US/docs/Web/JavaScript/Guide/Iterators_and_generators\">(async) iterator</a> to a readable stream:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const myReadableStream = ReadableStream.from(iteratorOrAsyncIterator);\n</code></pre></div>\n<p>On browsers that don't support the <code>from()</code> method you can instead create your own <a href=\"/en-US/docs/Web/API/Streams_API/Using_readable_streams#creating_your_own_custom_readable_stream\">custom readable stream</a> to achieve the same result:</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>function iteratorToStream(iterator) {\n return new ReadableStream({\n async pull(controller) {\n const { value, done } = await iterator.next();\n\n if (value) {\n controller.enqueue(value);\n }\n if (done) {\n controller.close();\n }\n },\n });\n}\n</code></pre></div>\n<div class=\"notecard warning\">\n <p><strong>Warning:</strong> This example assumes that the return value (<code>value</code> when <code>done</code> is <code>true</code>), if present, is also a chunk to be enqueued. Some iterator APIs may use the return value for different purposes. You may need to adjust the code based on the API you are interacting with.</p>\n</div>"}},{"type":"prose","value":{"id":"async_iteration_of_a_stream_using_for_await...of","title":"Async iteration of a stream using for await...of","isH3":true,"content":"<p>This example shows how you can process the <code>fetch()</code> response using a <a href=\"/en-US/docs/Web/JavaScript/Reference/Statements/for-await...of\"><code>for await...of</code></a> loop to iterate through the arriving chunks.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const response = await fetch(\"https://www.example.org\");\nlet total = 0;\n\n// Iterate response.body (a ReadableStream) asynchronously\nfor await (const chunk of response.body) {\n // Do something with each chunk\n // Here we just accumulate the size of the response.\n total += chunk.length;\n}\n\n// Do something with the total\nconsole.log(total);\n</code></pre></div>"}},{"type":"specifications","value":{"title":"Specifications","id":"specifications","isH3":false,"specifications":[{"bcdSpecificationURL":"https://streams.spec.whatwg.org/#rs-class","title":"Streams Standard"}],"query":"api.ReadableStream"}},{"type":"browser_compatibility","value":{"title":"Browser compatibility","id":"browser_compatibility","isH3":false,"query":"api.ReadableStream"}},{"type":"prose","value":{"id":"see_also","title":"See also","isH3":false,"content":"<ul>\n <li><a href=\"/en-US/docs/Web/API/Streams_API\">Streams API concepts</a></li>\n <li><a href=\"/en-US/docs/Web/API/Streams_API/Using_readable_streams\">Using readable streams</a></li>\n <li><a href=\"/en-US/docs/Web/API/Streams_API/Using_readable_byte_streams\">Using readable byte stream</a></li>\n <li><a href=\"https://whatwg-stream-visualizer.glitch.me/\" class=\"external\" target=\"_blank\">WHATWG Stream Visualizer</a>, for a basic visualization of readable, writable, and transform streams.</li>\n <li><a href=\"https://github.com/MattiasBuelens/web-streams-polyfill\" class=\"external\" target=\"_blank\">Web-streams-polyfill</a> or <a href=\"https://github.com/stardazed/sd-streams\" class=\"external\" target=\"_blank\">sd-streams</a> - polyfills</li>\n</ul>"}}],"toc":[{"text":"Constructor","id":"constructor"},{"text":"Instance properties","id":"instance_properties"},{"text":"Static methods","id":"static_methods"},{"text":"Instance methods","id":"instance_methods"},{"text":"Async iteration","id":"async_iteration"},{"text":"Examples","id":"examples"},{"text":"Specifications","id":"specifications"},{"text":"Browser compatibility","id":"browser_compatibility"},{"text":"See also","id":"see_also"}],"summary":"The ReadableStream interface of the Streams API represents a readable stream of byte data. The Fetch API offers a concrete instance of a ReadableStream through the body property of a Response object.","popularity":0.0434,"modified":"2024-08-30T05:24:07.000Z","other_translations":[{"locale":"de","title":"ReadableStream","native":"Deutsch"},{"locale":"ja","title":"ReadableStream","native":"日本語"},{"locale":"ko","title":"ReadableStream","native":"한국어"},{"locale":"zh-CN","title":"ReadableStream","native":"中文 (简体)"}],"pageType":"web-api-interface","source":{"folder":"en-us/web/api/readablestream","github_url":"https://github.com/mdn/content/blob/main/files/en-us/web/api/readablestream/index.md","last_commit_url":"https://github.com/mdn/content/commit/d8c0a74eec7281976ea1a4d13c57fecbed8ab70e","filename":"index.md"},"short_title":"ReadableStream","parents":[{"uri":"/en-US/docs/Web","title":"References"},{"uri":"/en-US/docs/Web/API","title":"Web APIs"},{"uri":"/en-US/docs/Web/API/ReadableStream","title":"ReadableStream"}],"pageTitle":"ReadableStream - Web APIs | MDN","noIndexing":false}}</script></body></html>