Object.assign.js

/**
 * Copyright 2014, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @providesModule Object.assign
 */

// https://people.mozilla.org/~jorendorff/es6-draft.html#sec-object.assign

function assign(target, sources) {
  if (target == null) {
    throw new TypeError('Object.assign target cannot be null or undefined');
  }

  var to = Object(target);
  var hasOwnProperty = Object.prototype.hasOwnProperty;

  for (var nextIndex = 1; nextIndex < arguments.length; nextIndex++) {
    var nextSource = arguments[nextIndex];
    if (nextSource == null) {
      continue;
    }

    var from = Object(nextSource);

    // We don't currently support accessors nor proxies. Therefore this
    // copy cannot throw. If we ever supported this then we must handle
    // exceptions and side-effects. We don't support symbols so they won't
    // be transferred.

    for (var key in from) {
      if (hasOwnProperty.call(from, key)) {
        to[key] = from[key];
      }
    }
  }

  return to;
};

module.exports = assign;