Firefox 66 для разработчиков


Developer tools


  • UTF-8-encoded HTML (and plain text) files loaded from file: URLs are now supported without <meta charset="utf-8"> or the UTF-8 BOM, making it easier to work on such files locally before uploading them to a server. You still need to make sure that the server sends charset=utf-8 in the Content-Type HTTP header for such files, otherwise the detection mechanism used for local files would break incremental loading in the network case (баг 1071816).




No additions.



No changes.


New APIs/changes

  • Autoplaying audio will be blocked by default soon after 66 becomes the release version of Firefox (баг 1487844, see баг 1535667 for rollout details). The feature will be rolled out gradually to users until everyone has it.


DOM events

  • The InputEvent.inputType property has been implemented (баг 1447239).
  • The Window.event and Event.returnValue properties — originally proprietary IE features, then also supported across other browsers for compatibility purposes — have been re-introduced in Firefox 66, after first being added in versions 63 and 64 respectively but then removed again due to compatibility issues. 
  • From 66 onwards, when the KeyboardEvent.keyCode property of the keypress event object is 0, the value will be the same as KeyboardEvent.charCode. Conversely, when charCode is 0, it will be the same as keyCode. This mirroring behavior matches other browsers and is expected to solve most associated compatibility issues, however user agent sniffing might cause further issues in some JavaScript libraries. Note that in spec terms, we've switched from the split model to the conflated model (see How to determine keyCode for keypress events in the UI Event spec).

Media, Web Audio, and WebRTC

  • The MediaDevices method getDisplayMedia(), available as navigator.mediaDevices.getDisplayMedia(), has been added and synchronized with the specification. This method lets you capture a screen or part of a screen as a MediaStream for manipulation or sharing (баг 1321221).
  • As a step toward eventually deprecating the Firefox-specific getUserMedia()-based method for capturing screen and window contents, the non-standard mediaSource constraint now treats the values screen and window identically. Both now present a list of both screens and windows for the user to choose from (баг 1474376).
  • qpSum has been added to local outbound RTCRTPStreamStats objects. This measures the total of the Quantization Parameter values for every frame sent or received on the video track. The higher this number, the more compressed the stream probably is (баг 1347070).
  • In a step along the road toward implementing support for Feature Policy in a future Firefox update, getUserMedia() can no longer be used in situations in which there is no proper origin for the content, such as when called from a sandboxed <iframe> or from a data URL entered into the address bar by the user. For more specifics and details, see Security в MediaDevices.getUserMedia() (баг 1371741).




No changes.


No changes.

Changes for add-on developers

API changes

  • Extension menu items of the "bookmark" type will also appear in the Bookmarks sidebar (Ctrl + B) and Library window (Ctrl + Shift + B) (баг 1419195).

Manifest changes

No changes.

See also

Older versions