The MediaRecorder.onstartevent handler (part of the MediaRecorder API) handles the start event, allowing you to run code in response to media recording being started by a MediaRecorder.
The start event is thrown as a result of the MediaRecorder.start() method being invoked. At this point, the data starts being gathered into a Blob.
Syntax
MediaRecorder.onstart = function(event) { ... }
MediaRecorder.addEventListener('start', function(event) { ... })
Example
...
  record.onclick = function() {
    mediaRecorder.start();
    console.log("recorder started");
  }
  mediaRecorder.onstart = function() {
    // do something in response to
    // recording being started
  }
...
Properties
None.
Specifications
| Specification | Status | Comment | 
|---|---|---|
| MediaStream Recording The definition of 'MediaRecorder.onstart' in that specification. | Working Draft | Initial definition | 
Browser compatibility
| Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari (WebKit) | 
|---|---|---|---|---|---|
| Basic support | 47[2] | 25.0 (25.0) | Not supported | Not supported | Not supported | 
| Feature | Android | Android Webview | Firefox Mobile (Gecko) | Firefox OS | IE Phone | Opera Mobile | Safari Mobile | Chrome for Android | 
|---|---|---|---|---|---|---|---|---|
| Basic support | Not supported | Not supported | 25.0 (25.0) | 1.3[1] | Not supported | Not supported | Not supported | Not supported | 
[1] The intial Firefox OS implementation only supported audio recording.
[2] To try this feature on Chrome, enable Experimental Web Platform features from chrome://flags . Currently only video is supported, not audio.
See also
- Using the MediaRecorder API
- Web Dictaphone: MediaRecorder + getUserMedia + Web Audio API visualization demo, by Chris Mills (source on Github.)
- simpl.info MediaStream Recording demo, by Sam Dutton.
- Navigator.getUserMedia