The Document.compatMode read-only property indicates whether the document is rendered in Quirks mode or Standards mode.
The Document.compatMode read-only property indicates whether the document is rendered in Quirks mode or Standards mode.
An enumerated value that can be:
BackCompat" if the document is in quirks mode.CSS1Compat" if the document is in no-quirks (also known as "standards") mode or limited-quirks (also known as "almost standards") mode. Note: All these modes are now standardized, so the older "standards" and "almost standards" names are nonsensical and no longer used in standards.
js
if (document.compatMode === "BackCompat") { // in Quirks mode }
| Specification |
|---|
| DOM Standard # ref-for-dom-document-compatmode① |
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
compatMode |
1 | 12 | 1 | 6 | ≤12.1 | 3.1 | 4.4 | 18 | 4 | ≤12.1 | 2 | 1.0 |
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https://developer.mozilla.org/en-US/docs/Web/API/Document/compatMode