The Document.compatMode read-only property indicates
whether the document is rendered in Quirks mode or
Standards mode.
Syntax
const mode = document.compatMode
Value
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.
Example
if (document.compatMode == "BackCompat") {
// in Quirks mode
}
Specifications
| Specification | Status | Comment |
|---|---|---|
| DOM The definition of 'compatMode' in that specification. |
Living Standard |
Browser compatibility
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