A BrowserSetting object whose underlying value is a boolean.

By default, of course, web pages can specify the fonts they want using CSS properties like font-family. This setting enables an extension to instruct Firefox to ignore the fonts specified by the page, and only use system fonts.

Its underlying value is a boolean:

  • true: use the fonts specified by the web page. This is the default.
  • false:  use the system fonts.

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxOperaSafariFirefox for Android
useDocumentFontsChrome No support NoEdge No support NoFirefox Full support 61Opera No support NoSafari No support NoFirefox Android Full support 61


Full support  
Full support
No support  
No support


Set the setting to false:

function logResult(result) {
  console.log(`Setting was modified: ${result}`);

browser.browserSettings.useDocumentFonts.set({value: false}).