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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="#example">Example</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/Channel_Messaging_API">Channel Messaging API</a></li><li class="section"><em><a href="/en-US/docs/Web/API/MessageChannel" aria-current="page"><code>MessageChannel</code></a></em></li><li class="toggle"><details open=""><summary>Constructor</summary><ol><li><a href="/en-US/docs/Web/API/MessageChannel/MessageChannel"><code>MessageChannel()</code></a></li></ol></details></li><li class="toggle"><details open=""><summary>Instance properties</summary><ol><li><a href="/en-US/docs/Web/API/MessageChannel/port1"><code>port1</code></a></li><li><a href="/en-US/docs/Web/API/MessageChannel/port2"><code>port2</code></a></li></ol></details></li><li class="toggle"><details open=""><summary>Related pages for Channel Messaging API</summary><ol><li><a href="/en-US/docs/Web/API/MessagePort"><code>MessagePort</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="#example">Example</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>MessageChannel</h1><details class="baseline-indicator high"><summary><span class="indicator" role="img" aria-label="Baseline Check"></span><h2>Baseline <span class="not-bold">Widely available</span></h2><div class="browsers"><span class="engine" title="Supported in Chrome and Edge"><span class="browser chrome supported" role="img" aria-label="Chrome check"></span><span class="browser edge supported" role="img" aria-label="Edge check"></span></span><span class="engine" title="Supported in Firefox"><span class="browser firefox supported" role="img" aria-label="Firefox check"></span></span><span class="engine" title="Supported in Safari"><span class="browser safari supported" role="img" aria-label="Safari check"></span></span></div><span class="icon icon-chevron "></span></summary><div class="extra"><p>This feature is well established and works across many devices and browser versions. It’s been available across browsers since September 2015.</p><ul><li><a href="/en-US/docs/Glossary/Baseline/Compatibility" data-glean="baseline_link_learn_more" target="_blank" class="learn-more">Learn more</a></li><li><a href="#browser_compatibility" data-glean="baseline_link_bcd_table">See full compatibility</a></li><li><a href="https://survey.alchemer.com/s3/7634825/MDN-baseline-feedback?page=%2Fen-US%2Fdocs%2FWeb%2FAPI%2FMessageChannel&level=high" data-glean="baseline_link_feedback" class="feedback-link" target="_blank" rel="noreferrer">Report feedback</a></li></ul></div></details></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 <strong><code>MessageChannel</code></strong> interface of the <a href="/en-US/docs/Web/API/Channel_Messaging_API">Channel Messaging API</a> allows us to create a new message channel and send data through it via its two <a href="/en-US/docs/Web/API/MessagePort"><code>MessagePort</code></a> properties.</p></div><section aria-labelledby="constructor"><h2 id="constructor"><a href="#constructor">Constructor</a></h2><div class="section-content"><dl> <dt id="messagechannel"><a href="/en-US/docs/Web/API/MessageChannel/MessageChannel" title="MessageChannel()"><code>MessageChannel()</code></a></dt> <dd> <p>Returns a new <code>MessageChannel</code> object with two new <a href="/en-US/docs/Web/API/MessagePort"><code>MessagePort</code></a> objects.</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="messagechannel.port1"><a href="/en-US/docs/Web/API/MessageChannel/port1"><code>MessageChannel.port1</code></a> <span class="badge inline readonly" title="This value may not be changed.">Read only </span></dt> <dd> <p>Returns port1 of the channel.</p> </dd> <dt id="messagechannel.port2"><a href="/en-US/docs/Web/API/MessageChannel/port2"><code>MessageChannel.port2</code></a> <span class="badge inline readonly" title="This value may not be changed.">Read only </span></dt> <dd> <p>Returns port2 of the channel.</p> </dd> </dl></div></section><section aria-labelledby="example"><h2 id="example"><a href="#example">Example</a></h2><div class="section-content"><p>In the following example, you can see a new channel being created using the <a href="/en-US/docs/Web/API/MessageChannel/MessageChannel" title="MessageChannel()"><code>MessageChannel()</code></a> constructor.</p> <p>When the IFrame has loaded, we register an <a href="/en-US/docs/Web/API/MessagePort/message_event" title="onmessage"><code>onmessage</code></a> handler for <a href="/en-US/docs/Web/API/MessageChannel/port1"><code>MessageChannel.port1</code></a> and transfer <a href="/en-US/docs/Web/API/MessageChannel/port2"><code>MessageChannel.port2</code></a> to the IFrame using the <a href="/en-US/docs/Web/API/Window/postMessage"><code>window.postMessage</code></a> method along with a message.</p> <p>When a message is received back from the IFrame, the <code>onMessage</code> function outputs the message to a paragraph.</p> <div class="code-example"><div class="example-header"><span class="language-name">js</span></div><pre class="brush: js notranslate"><code>const channel = new MessageChannel(); const output = document.querySelector(".output"); const iframe = document.querySelector("iframe"); // Wait for the iframe to load iframe.addEventListener("load", onLoad); function onLoad() { // Listen for messages on port1 channel.port1.onmessage = onMessage; // Transfer port2 to the iframe iframe.contentWindow.postMessage("Hello from the main page!", "*", [ channel.port2, ]); } // Handle messages received on port1 function onMessage(e) { output.innerHTML = e.data; } </code></pre></div> <p>For a full working example, see our <a href="https://github.com/mdn/dom-examples/tree/main/channel-messaging-basic" class="external" target="_blank">channel messaging basic demo</a> on GitHub (<a href="https://mdn.github.io/dom-examples/channel-messaging-basic/" class="external" target="_blank">run it live too</a>).</p></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://html.spec.whatwg.org/multipage/web-messaging.html#message-channels">HTML Standard <br/><small># message-channels</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/Channel_Messaging_API/Using_channel_messaging">Using channel messaging</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 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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/MessageChannel","doc":{"isMarkdown":true,"isTranslated":false,"isActive":true,"flaws":{},"title":"MessageChannel","mdn_url":"/en-US/docs/Web/API/MessageChannel","locale":"en-US","native":"English (US)","browserCompat":["api.MessageChannel"],"baseline":{"baseline":"high","baseline_high_date":"2018-03-22","baseline_low_date":"2015-09-22","support":{"chrome":"4","chrome_android":"18","edge":"12","firefox":"41","firefox_android":"41","safari":"5","safari_ios":"4.2"}},"sidebarHTML":"<ol><li class=\"section\"><a href=\"/en-US/docs/Web/API/Channel_Messaging_API\">Channel Messaging API</a></li><li class=\"section\"><em><a href=\"/en-US/docs/Web/API/MessageChannel\" aria-current=\"page\"><code>MessageChannel</code></a></em></li><li class=\"toggle\"><details open=\"\"><summary>Constructor</summary><ol><li><a href=\"/en-US/docs/Web/API/MessageChannel/MessageChannel\"><code>MessageChannel()</code></a></li></ol></details></li><li class=\"toggle\"><details open=\"\"><summary>Instance properties</summary><ol><li><a href=\"/en-US/docs/Web/API/MessageChannel/port1\"><code>port1</code></a></li><li><a href=\"/en-US/docs/Web/API/MessageChannel/port2\"><code>port2</code></a></li></ol></details></li><li class=\"toggle\"><details open=\"\"><summary>Related pages for Channel Messaging API</summary><ol><li><a href=\"/en-US/docs/Web/API/MessagePort\"><code>MessagePort</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 <strong><code>MessageChannel</code></strong> interface of the <a href=\"/en-US/docs/Web/API/Channel_Messaging_API\">Channel Messaging API</a> allows us to create a new message channel and send data through it via its two <a href=\"/en-US/docs/Web/API/MessagePort\"><code>MessagePort</code></a> properties.</p>"}},{"type":"prose","value":{"id":"constructor","title":"Constructor","isH3":false,"content":"<dl>\n <dt id=\"messagechannel\"><a href=\"/en-US/docs/Web/API/MessageChannel/MessageChannel\" title=\"MessageChannel()\"><code>MessageChannel()</code></a></dt>\n <dd>\n <p>Returns a new <code>MessageChannel</code> object with two new <a href=\"/en-US/docs/Web/API/MessagePort\"><code>MessagePort</code></a> objects.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"instance_properties","title":"Instance properties","isH3":false,"content":"<dl>\n <dt id=\"messagechannel.port1\"><a href=\"/en-US/docs/Web/API/MessageChannel/port1\"><code>MessageChannel.port1</code></a> <span class=\"badge inline readonly\" title=\"This value may not be changed.\">Read only </span></dt>\n <dd>\n <p>Returns port1 of the channel.</p>\n </dd>\n <dt id=\"messagechannel.port2\"><a href=\"/en-US/docs/Web/API/MessageChannel/port2\"><code>MessageChannel.port2</code></a> <span class=\"badge inline readonly\" title=\"This value may not be changed.\">Read only </span></dt>\n <dd>\n <p>Returns port2 of the channel.</p>\n </dd>\n</dl>"}},{"type":"prose","value":{"id":"example","title":"Example","isH3":false,"content":"<p>In the following example, you can see a new channel being created using the <a href=\"/en-US/docs/Web/API/MessageChannel/MessageChannel\" title=\"MessageChannel()\"><code>MessageChannel()</code></a> constructor.</p>\n<p>When the IFrame has loaded, we register an <a href=\"/en-US/docs/Web/API/MessagePort/message_event\" title=\"onmessage\"><code>onmessage</code></a> handler for <a href=\"/en-US/docs/Web/API/MessageChannel/port1\"><code>MessageChannel.port1</code></a> and transfer <a href=\"/en-US/docs/Web/API/MessageChannel/port2\"><code>MessageChannel.port2</code></a> to the IFrame using the <a href=\"/en-US/docs/Web/API/Window/postMessage\"><code>window.postMessage</code></a> method along with a message.</p>\n<p>When a message is received back from the IFrame, the <code>onMessage</code> function outputs the message to a paragraph.</p>\n<div class=\"code-example\"><div class=\"example-header\"><span class=\"language-name\">js</span></div><pre class=\"brush: js notranslate\"><code>const channel = new MessageChannel();\nconst output = document.querySelector(\".output\");\nconst iframe = document.querySelector(\"iframe\");\n\n// Wait for the iframe to load\niframe.addEventListener(\"load\", onLoad);\n\nfunction onLoad() {\n // Listen for messages on port1\n channel.port1.onmessage = onMessage;\n\n // Transfer port2 to the iframe\n iframe.contentWindow.postMessage(\"Hello from the main page!\", \"*\", [\n channel.port2,\n ]);\n}\n\n// Handle messages received on port1\nfunction onMessage(e) {\n output.innerHTML = e.data;\n}\n</code></pre></div>\n<p>For a full working example, see our <a href=\"https://github.com/mdn/dom-examples/tree/main/channel-messaging-basic\" class=\"external\" target=\"_blank\">channel messaging basic demo</a> on GitHub (<a href=\"https://mdn.github.io/dom-examples/channel-messaging-basic/\" class=\"external\" target=\"_blank\">run it live too</a>).</p>"}},{"type":"specifications","value":{"title":"Specifications","id":"specifications","isH3":false,"specifications":[{"bcdSpecificationURL":"https://html.spec.whatwg.org/multipage/web-messaging.html#message-channels","title":"HTML Standard"}],"query":"api.MessageChannel"}},{"type":"browser_compatibility","value":{"title":"Browser compatibility","id":"browser_compatibility","isH3":false,"query":"api.MessageChannel"}},{"type":"prose","value":{"id":"see_also","title":"See also","isH3":false,"content":"<ul>\n <li><a href=\"/en-US/docs/Web/API/Channel_Messaging_API/Using_channel_messaging\">Using channel messaging</a></li>\n</ul>"}}],"toc":[{"text":"Constructor","id":"constructor"},{"text":"Instance properties","id":"instance_properties"},{"text":"Example","id":"example"},{"text":"Specifications","id":"specifications"},{"text":"Browser compatibility","id":"browser_compatibility"},{"text":"See also","id":"see_also"}],"summary":"The MessageChannel interface of the Channel Messaging API allows us to create a new message channel and send data through it via its two MessagePort properties.","popularity":0.0039,"modified":"2024-03-06T06:22:42.000Z","other_translations":[{"locale":"de","title":"MessageChannel","native":"Deutsch"},{"locale":"ja","title":"MessageChannel","native":"日本語"},{"locale":"pt-BR","title":"MessageChannel","native":"Português (do Brasil)"},{"locale":"zh-CN","title":"MessageChannel","native":"中文 (简体)"}],"pageType":"web-api-interface","source":{"folder":"en-us/web/api/messagechannel","github_url":"https://github.com/mdn/content/blob/main/files/en-us/web/api/messagechannel/index.md","last_commit_url":"https://github.com/mdn/content/commit/e4c0939929e1b3e1fa3fd3da82b827fca3ed4c79","filename":"index.md"},"short_title":"MessageChannel","parents":[{"uri":"/en-US/docs/Web","title":"References"},{"uri":"/en-US/docs/Web/API","title":"Web APIs"},{"uri":"/en-US/docs/Web/API/MessageChannel","title":"MessageChannel"}],"pageTitle":"MessageChannel - Web APIs | MDN","noIndexing":false}}</script></body></html>