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.
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.
js
const iframeDocument = document.querySelector("iframe").contentDocument; iframeDocument.body.style.backgroundColor = "blue"; // This would turn the iframe blue.
| Specification | 
|---|
| HTML Standard  # dom-iframe-contentdocument  | 
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
contentDocument | 
1 | 12 | 1 | 8 | ≤12.1 | 3 | 4.4 | 18 | 4 | ≤12.1 | 1 | 1.0 | 
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    https://developer.mozilla.org/en-US/docs/Web/API/HTMLIFrameElement/contentDocument