modernizr/feature-detects/es6/promises.js

Modernizr is a JavaScript library that detects HTML5 and CSS3 features in the user’s browser.

/*!
{
  "name": "ES6 Promises",
  "property": "promises",
  "caniuse": "promises",
  "polyfills": ["es6promises"],
  "authors": ["Krister Kari", "Jake Archibald"],
  "tags": ["es6"],
  "notes": [{
    "name": "The ES6 promises spec",
    "href": "https://github.com/domenic/promises-unwrapping"
  },{
    "name": "Chromium dashboard - ES6 Promises",
    "href": "https://www.chromestatus.com/features/5681726336532480"
  },{
    "name": "JavaScript Promises: There and back again - HTML5 Rocks",
    "href": "http://www.html5rocks.com/en/tutorials/es6/promises/"
  }]
}
!*/
/* DOC
Check if browser implements ECMAScript 6 Promises per specification.
*/
define(['Modernizr'], function(Modernizr) {
  Modernizr.addTest('promises', function() {
    return 'Promise' in window &&
    // Some of these methods are missing from
    // Firefox/Chrome experimental implementations
    'resolve' in window.Promise &&
    'reject' in window.Promise &&
    'all' in window.Promise &&
    'race' in window.Promise &&
    // Older version of the spec had a resolver object
    // as the arg rather than a function
    (function() {
      var resolve;
      new window.Promise(function(r) { resolve = r; });
      return typeof resolve === 'function';
    }());
  });
});