Non-standard: This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

Note: Since Firefox 57 (initially Nightly-only), both the content and _content variants are only available to chrome (privileged) code, and not available to the web anymore.

Returns a Window object for the primary content window. This is useful in XUL windows that have a <browser> (or tabbrowser or <iframe>) with type="content-primary" attribute on it — the most famous example is Firefox main window, browser.xul. In such cases, content returns a reference to the Window object for the document currently displayed in the browser. It is a shortcut for browserRef.contentWindow.

In unprivileged content (webpages), content is normally equivalent to top (except in the case of a webpage loaded in a sidebar, content still refers to the Window of the currently selected tab).

Note: Some examples use _content instead of content. The former has been deprecated for a long time, and you should use content in any new code.


const windowObject = window.content


Executing the following code in a chrome XUL window with a <browser type="content-primary"/> element in it draws a red border around the first div on the page currently displayed in the browser:

content.document.querySelector("div").style.border = "solid red 1px";



See also