Revision 1125971 of Chrome incompatibilities

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<p>WebExtensions are designed to be compatible with Chrome and Opera extensions: as far as possible, extensions written for those browsers should run on Firefox with minimal changes.</p>

<p>However, Firefox currently has support for only a limited set of the features and APIs supported by Chrome and Opera. We're working on adding more support, but many features are not yet supported, and we may never support some.</p>

<p>This article lists all features and APIs that are fully or partially supported in Firefox Developer Edition (currently Firefox 47). Where a feature is partially supported, we've indicated what the gaps are.</p>

<div class="note">
<p>You should assume that features and APIs not listed here at all are not yet supported.</p>
</div>

<h2 id="manifest.json_features"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json">manifest.json</a> features</h2>

<h3 id="Fully_supported_keys">Fully supported keys</h3>

<ul>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/applications">applications</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/browser_action">browser_action</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/default_locale">default_locale</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/description">description</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/icons">icons</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/manifest_version">manifest_version</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/name">name</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/page_action">page_action</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/version">version</a></code></li>
 <li><code><a href="/en-US/Add-ons/WebExtensions/manifest.json/web_accessible_resources">web_accessible_resources</a></code></li>
</ul>

<h3 id="Partially_supported_keys">Partially supported keys</h3>

<h4 id="background"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/background">background</a></h4>

<p>Firefox does not support the <code>"persistent"</code> property. Background scripts stay loaded all the time.</p>

<h4 id="commands"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/commands">commands</a></h4>

<p>Firefox does not support:</p>

<ul>
 <li>Media keys as shortcuts</li>
 <li><code>global</code></li>
 <li>the special command <code>_execute_browser_action</code></li>
</ul>

<h4 id="content_scripts"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_scripts">content_scripts</a></h4>

<p>Firefox does not support:</p>

<ul>
 <li><code>match_about_blank</code></li>
</ul>

<h4 id="content_security_policy"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/content_security_policy">content_security_policy</a></h4>

<p>Firefox does not support:</p>

<ul>
 <li>"https://127.0.0.1" or "https://localhost" as script sources: they must be served over HTTPS.</li>
</ul>

<h4 id="options_ui"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/options_ui">options_ui</a></h4>

<p>Firefox does not support:</p>

<ul>
 <li><code>chrome_style</code></li>
</ul>

<p>Using <code>options_ui</code> requires a valid value for the <a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/applications">applications.gecko.id</a> property.</p>

<h4 id="permissions"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions">permissions</a></h4>

<p>Firefox does not support the following permissions:</p>

<ul>
 <li><code>background</code></li>
 <li><code>clipboardRead</code></li>
 <li><code>clipboardWrite</code></li>
 <li><code>geolocation</code></li>
 <li><code>unlimitedStorage</code></li>
</ul>

<p>Obviously, it doesn't support permissions for APIs that are themselves not supported.</p>

<h4 id="incognito">incognito</h4>

<p>Firefox does not support the following incognito (private browsing) modes:</p>

<ul>
 <li><code>split</code></li>
</ul>

<h2 id="JavaScript_APIs">JavaScript APIs</h2>

<h3 id="Fully_supported_APIs">Fully supported APIs</h3>

<ul>
 <li><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/alarms">alarms</a></li>
 <li><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/browserAction">browserAction</a>
  <ul>
   <li>Relative URLs passed to <code>setPopup()</code> are resolved relative to the caller document, rather than to the extension root</li>
  </ul>
 </li>
 <li><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/commands">commands</a></li>
 <li><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/contextMenus">contextMenus</a></li>
 <li><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/cookies">cookies</a></li>
 <li><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/i18n">i18n</a></li>
 <li><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/pageAction">pageAction</a>
  <ul>
   <li>Relative URLs passed to <code>setPopup()</code> are resolved relative to the caller document, rather than to the extension root</li>
  </ul>
 </li>
</ul>

<h3 id="Partially_supported_APIs">Partially supported APIs</h3>

<h4 id="bookmarks"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/bookmarks">bookmarks</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>import()</code></li>
   <li><code>export()</code></li>
   <li><code>onCreated</code></li>
   <li><code>onRemoved</code></li>
   <li><code>onChanged</code></li>
   <li><code>onMoved</code></li>
   <li><code>onChildrenReordered</code></li>
   <li><code>onImportBegan</code></li>
   <li><code>onImportEnded</code></li>
   <li><code>BookmarkTreeNodeUnmodifiable</code></li>
  </ul>
 </li>
 <li>Firefox has special bookmarks like "Recently Bookmarked" or "Recently Visited"</li>
</ul>

<h4 id="contextMenus"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/contextMenus">contextMenus</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li>the "browser_action" or "page_action" context types</li>
  </ul>
 </li>
</ul>

<h4 id="downloads"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/downloads">downloads</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>drag()</code></li>
   <li><code>acceptDanger()</code></li>
   <li><code>setShelfEnabled()</code></li>
   <li><code>onDeterminingFilename</code></li>
  </ul>
 </li>
 <li>The <code>saveAs</code> option and values other than <code>"GET"</code> for the <code>method</code> option are not supported by <code>download()</code></li>
</ul>

<h4 id="extension"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/extension">extension</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>setUpdateUrlData()</code></li>
  </ul>
 </li>
 <li>Additionally, the following deprecated properties will not be supported:
  <ul>
   <li><code>onRequest</code></li>
   <li><code>onRequestExternal</code></li>
   <li><code>getExtensionTabs()</code></li>
   <li><code>sendRequest()</code></li>
  </ul>
 </li>
</ul>

<h4 id="idle"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/idle">idle</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>onStateChanged</code></li>
   <li><code>setDetectionInterval()</code></li>
  </ul>
 </li>
</ul>

<p>Additoinally, <code>queryState()</code> always returns <code>"active"</code> in Firefox, regardless of the current system idle state.</p>

<h4 id="management"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/management">management</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code><span class="str">LaunchType</span></code></li>
   <li><code><span class="str">get</span>()</code></li>
   <li><code><span class="str">getAll()</span></code></li>
   <li><code><span class="str">getPermissionWarningsById()</span></code></li>
   <li><code><span class="str">getPermissionWarningsByManifest()</span></code></li>
   <li><code><span class="str">setEnabled</span>()</code></li>
   <li><code><span class="str">uninstall()</span></code></li>
   <li><code><span class="str">launchApp()</span></code></li>
   <li><code><span class="str">createAppShortcut()</span></code></li>
   <li><code><span class="str">setLaunchType()</span></code></li>
   <li><code><span class="str">generateAppForLink()</span></code></li>
   <li><code><span class="str">onInstalled</span></code></li>
   <li><code><span class="str">onUninstalled</span></code></li>
   <li><code><span class="str">onEnabled</span></code></li>
   <li><code><span class="str">onDisabled</span></code></li>
  </ul>
 </li>
</ul>

<h4 id="notifications"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/notifications">notifications</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>update()</code></li>
   <li><code>onButtonClicked</code></li>
  </ul>
 </li>
 <li>Firefox doesn't provide <code>byUser</code> data.</li>
 <li>Firefox only supports the <code>"basic"</code> <code><a href="/en-US/Add-ons/WebExtensions/API/notifications/TemplateType">type</a>.</code></li>
 <li>For <code>chrome.notifications.create(), with the "basic"</code> <code><a href="/en-US/Add-ons/WebExtensions/API/notifications/TemplateType">type</a></code>, <code>iconUrl</code> is optional in Firefox. It is required in Chrome.</li>
 <li>Notifications are cleared immediately when the user clicks on them. This is not the case in Chrome.</li>
 <li>If you call <code>chrome.notifications.create()</code> more than once in rapid succession, Firefox may end up not displaying any notification at all. Waiting to make subsequent calls until within the <code>chrome.notifications.create() callback</code> function is not a sufficiently long delay to prevent this from happening.</li>
 <li>If the <code>iconUrl</code> property is present, but invalid when <code>chrome.notifications.create() is called</code>, the notification will be displayed with space for the icon, but without the icon. In Chrome, the notification will not be displayed, an error will be shown in the extension's background page console and <code>runtime.lastError</code> will be set in the callback function.</li>
</ul>

<h4 id="runtime"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/runtime">runtime</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>getPackageDirectoryEntry()</code></li>
   <li><code>reload()</code></li>
   <li><code>requestUpdateCheck()</code></li>
   <li><code>restart()</code></li>
   <li><code>sendNativeMessage()</code></li>
   <li><code>onBrowserUpdateAvailable</code></li>
   <li><code>onConnectExternal</code></li>
   <li><code>onInstalled</code></li>
   <li><code>onMessageExternal</code></li>
   <li><code>onRestartRequired</code></li>
   <li><code>onStartup</code></li>
   <li><code>onSuspend</code></li>
   <li><code>onSuspendCanceled</code></li>
   <li><code>onUpdateAvailable</code></li>
  </ul>
 </li>
 <li><code>runtime.lastError</code> is a string in Firefox. In Chrome, it is an <code>Object</code> with the error text as the <code>string</code> value of the <code>message</code> property.</li>
</ul>

<h4 id="storage"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/storage">storage</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>managed</code> storage area</li>
   <li><code>sync</code> storage area</li>
   <li><code>getBytesInUse()</code>.</li>
  </ul>
 </li>
</ul>

<h4 id="tabs"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs">tabs</a></h4>

<ul>
 <li>Firefox treats <code>highlighted</code> and <code>active</code> as the same, since Firefox has no concept of selecting multiple tabs.</li>
 <li>In Firefox, you need the <code>tabs</code> <a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/manifest.json/permissions">permission</a> if you want to include <code>url</code> in the <code>queryInfo</code> parameter to <code><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/tabs/query">tabs.query()</a></code>.</li>
 <li>
  <p>In Firefox, relative URLs passed into <code>tabs.executeScript()</code> or <code>tabs.insertCSS()</code> are resolved relative to the current page URL. In Chrome, these URLs are resolved relative to the add-on's base URL. To work cross-browser, you can specify the path as an absolute URL, starting at the add-on's root, like this:</p>

  <pre class="line-numbers  language-html">
<code class="language-html">/path/to/script.js</code></pre>
 </li>
 <li>In Firefox, you can't open (using {{WebExtAPIRef("tabs.create")}}), or navigate to (using {{WebExtAPIRef("tabs.update")}}) privileged URLs:
  <ul>
   <li>chrome: URLs</li>
   <li>javascript: URLs</li>
   <li>data: URLs</li>
   <li>privileged about: URLs (for example, about:config, about:addons, about:debugging)</li>
  </ul>
 </li>
 <li>Additionally, the following deprecated properties will not be supported:
  <ul>
   <li><code>sendRequest()</code></li>
   <li><code>getSelected()</code></li>
   <li><code>onActiveChanged</code></li>
   <li><code>onHighlightChanged</code></li>
   <li><code>onSelectionChanged</code></li>
  </ul>
 </li>
</ul>

<h4 id="webNavigation"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/webNavigation">webNavigation</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>onCreatedNavigationTarget</code></li>
   <li><code>onTabReplaced</code></li>
  </ul>
 </li>
</ul>

<h4 id="webRequest"><a href="/en-US/docs/User%3Awbamberg/WebExtensions/API/webRequest">webRequest</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li><code>onAuthRequired</code></li>
   <li>filtering by <code>windowId</code> and <code>tabId</code></li>
   <li>the <code>"requestBody"</code> instruction in <code>opt_extraInfoSpec</code></li>
  </ul>
 </li>
 <li>In Firefox requests can be redirected only if their original URL uses the http or https scheme</li>
</ul>

<h4 id="windows"><a href="/en-US/docs/Mozilla/Add-ons/WebExtensions/API/windows">windows</a></h4>

<ul>
 <li>Firefox does not support:
  <ul>
   <li>the <code>focused </code>option in <code>create()</code></li>
  </ul>
 </li>
 <li>In Firefox <code>onFocusChanged</code> will trigger multiple times for a given focus change.</li>
</ul>

<h3 id="Planned_APIs">Planned APIs</h3>

<p>We don't support the following APIs, but plan to, soon:</p>

<ul>
 <li><a class="external text" href="https://developer.chrome.com/extensions/devtools" rel="nofollow">Devtools (mostly panels)</a></li>
 <li><a href="https://developer.chrome.com/extensions/debugger">debugger</a></li>
 <li><a class="external text" href="https://developer.chrome.com/extensions/omnibox" rel="nofollow">omnibox</a></li>
 <li><a class="external text" href="https://developer.chrome.com/extensions/permissions" rel="nofollow">permissions</a></li>
</ul>

<p>This doesn't mean that these are the only additional APIs we will support, but that they are our current priorities.</p>

<h3 id="Miscellaneous_incompatibilities">Miscellaneous incompatibilities</h3>

<h4 id="Optional_arguments">Optional arguments</h4>

<h4 id="URLs_in_CSS">URLs in CSS</h4>

<p>Firefox resolves URLs in injected CSS files relative to the CSS file itself, rather than to the page it's injected into.</p>

<h4 id="Additional_incompatibilities">Additional incompatibilities</h4>

<p>Firefox does not support using <code><a href="/en-US/docs/Web/API/Window/alert">alert()</a></code> from background pages. Using <code>alert(message)</code> from a background page will cause the <a href="/en-US/docs/Tools/Browser_Console">Browser Console</a> to be opened and both a line stating "alert() is not supported in background windows; please use console.log instead." and the <code>message</code> will be output to the console.</p>

<p>Firefox does not support <a href="/en-US/docs/Web/API/Window/confirm">confirm()</a> from background pages. Using confirm(message) will result in a error being thrown.</p>

<p>Firefox does not support <a href="/en-US/docs/Web/API/Window/prompt">prompt()</a> from background pages. Using prompt(message) will result in a error being thrown.</p>