raptor-polyfill/object/assign.js

Polyfills for various EcmaScript 5 and EcmaScript 6 methods distributed as CommonJS modules that can be require'd individually or as a whole.

// ES6 19.1.2.1
// http://www.ecma-international.org/ecma-262/6.0/#sec-object.assign
// https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/assign#Polyfill
if (typeof Object.assign != 'function') {
  Object.assign = function(target, varArgs) { // .length of function is 2
    'use strict';
    if (target == null) { // TypeError if undefined or null
      throw new TypeError('Cannot convert undefined or null to object');
    }

    var to = Object(target);

    for (var index = 1; index < arguments.length; index++) {
      var nextSource = arguments[index];

      if (nextSource != null) { // Skip over if undefined or null
        for (var nextKey in nextSource) {
          // Avoid bugs when hasOwnProperty is shadowed
          if (Object.prototype.hasOwnProperty.call(nextSource, nextKey)) {
            to[nextKey] = nextSource[nextKey];
          }
        }
      }
    }
    return to;
  };
}