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MediaDevices.getSupportedConstraints() - Web APIs 编辑

The getSupportedConstraints() method of the MediaDevices interface returns an object based on the MediaTrackSupportedConstraints dictionary, whose member fields each specify one of the constrainable properties the user agent understands.

Syntax

var supportedConstraints = navigator.mediaDevices.getSupportedConstraints();

Parameters

None.

Return value

A new object based on the MediaTrackSupportedConstraints dictionary listing the constraints supported by the user agent. Because only constraints supported by the user agent are included in the list, each of these Boolean properties has the value true.

Example

This example outputs a list of the constraints supported by your browser.

HTML

<p>The following media constraints are supported by your browser:</p>

<ul id="constraintList">
</ul>

CSS

body {
  font: 15px Arial, sans-serif;
}

JavaScript

let constraintList = document.getElementById("constraintList");
let supportedConstraints = navigator.mediaDevices.getSupportedConstraints();

for (let constraint in supportedConstraints) {
  if (supportedConstraints.hasOwnProperty(constraint)) {
    let elem = document.createElement("li");

    elem.innerHTML = "<code>" + constraint + "</code>";
    constraintList.appendChild(elem);
  }
}