MediaTrackSupportedConstraints: aspectRatio property
  The MediaTrackSupportedConstraints dictionary's aspectRatio property is a read-only Boolean value which is present (and set to true) in the object returned by MediaDevices.getSupportedConstraints() if and only if the
  user agent supports the aspectRatio constraint.
  If the constraint isn't supported, it's not included in the list, so this value will never be false.
You can access the supported constraints dictionary by calling navigator.mediaDevices.getSupportedConstraints().
Value
  This property is present in the dictionary (and its value is always true)
  if the user agent supports the aspectRatio constraint. If the property
  isn't present, this property is missing from the supported constraints dictionary, and
  you'll get undefined if you try to look at its value.
Examples
const result = document.getElementById("result");
const supported = navigator.mediaDevices.getSupportedConstraints().aspectRatio;
result.textContent = supported ? "Supported!" : "Not supported!";
Result
Specifications
| Specification | 
|---|
| Media Capture and Streams # dom-mediatrackconstraintset-aspectratio | 
Browser compatibility
BCD tables only load in the browser