Firefox 50 for developers

To test the latest developer features of Firefox, install Firefox Developer Edition. Firefox 50 was released on November 15, 2016. This article lists key changes that are useful not only for web developers, but also Firefox and Gecko developers as well as add-on developers.

Changes for Web developers

HTML

CSS

JavaScript

Developer Tools

HTTP

Security

Networking

DOM

SVG

Drag and Drop API

Pointer Lock API

IndexedDB

Service Workers

WebGL

WebRTC

  • Adding a track to a MediaStream now generates the addtrack event as described in the specification. The event is of type MediaStreamTrackEvent and is fired on the stream to which the track was added. You can use either MediaStream.addEventListener('addtrack', ...) or the onaddtrack property to handle "addtrack" events.
  • The MediaStreamTrack interface now supports the ended event and its event handler.
  • Firefox now supports the MediaStreamTrack.readyState property, which indicates whether the track is live or permanently ended.
  • The MediaStreamTrack methods getConstraints() and getSettings() have been implemented; these let you get the most recently applied set of customized property constraints and the actual values of all of the track's constrainable properties, respectively. The accompanying data types have been documented as well.
  • The RTCDataChannel.stream property has been removed. This was replaced with RTCDataChannel.id in Firefox 24, but was supported for backward compatibility. Please be sure to update your code to use the id property if you haven't done so yet.

Web Audio API

Audio/Video

Battery API

Files and directories

Older versions