react/React/createObjectFrom.js

/**
 * Copyright 2013 Facebook, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @providesModule createObjectFrom
 */

var hasArrayNature = require("./hasArrayNature");

/**
 * Construct an object from an array of keys
 * and optionally specified value or list of values.
 *
 *  >>> createObjectFrom(['a','b','c']);
 *  {a: true, b: true, c: true}
 *
 *  >>> createObjectFrom(['a','b','c'], false);
 *  {a: false, b: false, c: false}
 *
 *  >>> createObjectFrom(['a','b','c'], 'monkey');
 *  {c:'monkey', b:'monkey' c:'monkey'}
 *
 *  >>> createObjectFrom(['a','b','c'], [1,2,3]);
 *  {a: 1, b: 2, c: 3}
 *
 *  >>> createObjectFrom(['women', 'men'], [true, false]);
 *  {women: true, men: false}
 *
 * @param   Array   list of keys
 * @param   mixed   optional value or value array.  defaults true.
 * @returns object
 */
function createObjectFrom(keys, values /* = true */) {
  if (true) {
    if (!hasArrayNature(keys)) {
      throw new TypeError('Must pass an array of keys.');
    }
  }

  var object = {};
  var is_array = hasArrayNature(values);
  if (typeof values == 'undefined') {
    values = true;
  }

  for (var ii = keys.length; ii--;) {
    object[keys[ii]] = is_array ? values[ii] : values;
  }
  return object;
}

module.exports = createObjectFrom;