MediaTrackSupportedConstraints: echoCancellation property
  The MediaTrackSupportedConstraints dictionary's
  echoCancellation 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 echoCancellation 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 echoCancellation 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().echoCancellation;
result.textContent = supported ? "Supported!" : "Not supported!";
Result
Specifications
| Specification | 
|---|
| Media Capture and Streams # dom-mediatrackconstraintset-echocancellation | 
Browser compatibility
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