The getConstraints() method of the MediaStreamTrack interface returns a MediaTrackConstraints object containing the set of constraints most recently established for the track using a prior call to applyConstraints(). These constraints indicate values and ranges of values that the Web site or application has specified are acceptable for the included constrainable properties.

Constraints can be used to ensure that the media meets certain guidelines you prefer. For example, you may prefer high density video but require that the frame rate be a little low to help keep the data rate low enough not overtax the network. Constraints can also specify ideal and/or acceptable sizes or ranges of sizes. See "Capabilities and constraints" in Media Capture and Streams API (Media Streams) for details on how to work with constrainable properties.


var constraints = MediaStreamTrack.getConstraints();



Return value

MediaTrackConstraints object which indicates the constrainable properties the Web site or app most recently set using applyConstraints(). The properties in the returned object are listed in the same order as when they were set, and no properties not specifically set by the site or app are included.

The returned set of constraints may not actually match those in effect; if any of the constraints couldn't be met, they are still included in the returned object as originally set by the site's code. To get the currently active settings for all constrainable properties, you should instead call getSettings().


Specification Status Comment
Media Capture and Streams
The definition of 'getConstraints()' in that specification.
Editor's Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Internet Explorer Opera Safari
Basic support 53.0 50 (50) ? ? ?
Feature Android Android Webview Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile Chrome for Android
Basic support No support 53.0 50.0 (50) ? ? ? 52.0


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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.

API getConstraints Media Capture and Streams Media Streams API MediaStreamTrack Method Reference