How do I detect if the HTML5 autoplay attribute is supported?

Question

How do I best detect whether a browser\'s HTML5 video element supports autoplay?

On current iOS Safari, for example, autoplay is disabled.

Update:

Answer 1

Modernizr autoplay test has some reliability issues, as pointed here: https://github.com/Modernizr/Modernizr/issues/1095

You can detect video autoplay support by checking if the paused status of a video element changes after it programmatically plays. This alone can return false negatives in some mobile browsers, so a Promise check should be added in order to cover these.

This method works in all major browsers (desktop and mobile), except for Android <= 4.0 and Windows Phone, where it returns a false negative.

Here is the detect function:

var supports_video_autoplay = function(callback) {

  if (typeof callback !== "function") return false;

  var v = document.createElement("video");
  v.paused = true;
  var p = "play" in v && v.play();

  callback(!v.paused || ("Promise" in window && p instanceof Promise));

};

Usage:

supports_video_autoplay(function(supported) {
  if (supported) {
    // video autoplay supported!
  } else {
    // no video autoplay support :(
  }
});

Live test: https://codepen.io/paulorely/pen/QveEGy