core-js/modules/es.array.sort.js

'use strict';
var $ = require('../internals/export');
var aFunction = require('../internals/a-function');
var toObject = require('../internals/to-object');
var fails = require('../internals/fails');
var sloppyArrayMethod = require('../internals/sloppy-array-method');

var nativeSort = [].sort;
var test = [1, 2, 3];

// IE8-
var FAILS_ON_UNDEFINED = fails(function () {
  test.sort(undefined);
});
// V8 bug
var FAILS_ON_NULL = fails(function () {
  test.sort(null);
});
// Old WebKit
var SLOPPY_METHOD = sloppyArrayMethod('sort');

var FORCED = FAILS_ON_UNDEFINED || !FAILS_ON_NULL || SLOPPY_METHOD;

// `Array.prototype.sort` method
// https://tc39.github.io/ecma262/#sec-array.prototype.sort
$({ target: 'Array', proto: true, forced: FORCED }, {
  sort: function sort(comparefn) {
    return comparefn === undefined
      ? nativeSort.call(toObject(this))
      : nativeSort.call(toObject(this), aFunction(comparefn));
  }
});