If the iframe and the iframe's parent document are Same Origin, returns a Document (that is, the active document in the inline frame's nested browsing context), else returns null.

Example of contentDocument

var iframeDocument = document.getElementsByTagName("iframe")[0].contentDocument; = "blue";
// This would turn the iframe blue.


Specification Status Comment
HTML Living Standard
The definition of 'HTMLIFrameElement: contentDocument' in that specification.
Living Standard

Browser compatibility

BCD tables only load in the browser