MediaTrackConstraints: aspectRatio property
  The MediaTrackConstraints dictionary's aspectRatio property is a ConstrainDouble describing the requested or mandatory constraints placed upon the value of the
  aspectRatio constrainable property.
  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.
Value
  A ConstrainDouble describing the acceptable or required value(s) for a
  video track's aspect ratio. The value is the width divided by the height and is rounded
  to ten decimal places. For example, the standard high-definition video aspect ratio of
  16:9 can be computed as 1920/1080, or 1.7777777778.
  If this value is a number, the user agent will attempt to obtain media whose aspect
  ratio is as close as possible to this number given the capabilities of the hardware and
  the other constraints specified. Otherwise, the value of this
  ConstrainDouble will guide the user agent in its efforts to provide an
  exact match to the required aspect ratio (if exact is specified or both
  min and max are provided and have the same value) or to a
  best-possible value.
Examples
See the Constraint exerciser example.
Specifications
| Specification | 
|---|
| Media Capture and Streams # dom-mediatrackconstraintset-aspectratio | 
Browser compatibility
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