document.compatMode

Indicates whether the document is rendered in Quirks mode or Standards mode.

Syntax

mode = document.compatMode;

Values

mode

Is 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.

Example

if (document.compatMode == "BackCompat") {
  // in Quirks mode
}

Specifications

• DOM: Document.compatMode

Browser compatibilityUpdate compatibility data on GitHub