The MediaTrackSettings dictionary's aspectRatio property is a double-precision floating-point number indicating the aspect ratio of the MediaStreamTrack as currently configured. This lets you determine what value was selected to comply with your specified constraints for this property's value as described in the MediaTrackConstraints.aspectRatio property you provided when calling either getUserMedia() or MediaStreamTrack.applyConstraints().

If needed, you can determine whether or not this constraint is supported by checking the value of MediaTrackSupportedConstraints.aspectRatio as returned by a call to MediaDevices.getSupportedConstraints(). However, typically this is unnecessary since browsers will ignore any constraints they're unfamiliar with.

A double-precision floating-point number indicating the current configuration of the track's aspect ratio. The aspect ratio is computed by taking the track's width, dividing by its height, and rounding the result to ten decimal places. For example, the standard 16:9 high-definition aspect ratio can be computed as 1920/1080, or 1.7777777778.

See the Constraint exerciser example.

• Media Capture and Streams API
• Capabilities, constraints, and settings
• MediaTrackConstraints.aspectRatio
• MediaTrackSettings