lodash/utility/propertyOf.js

define([], function() {

  /** Used as a safe reference for `undefined` in pre-ES5 environments. */
  var undefined;

  /**
   * The inverse of `_.property`; this method creates a function which returns
   * the property value of a given key on `object`.
   *
   * @static
   * @memberOf _
   * @category Utility
   * @param {Object} object The object to inspect.
   * @returns {Function} Returns the new function.
   * @example
   *
   * var object = { 'user': 'fred', 'age': 40, 'active': true };
   * _.map(['active', 'user'], _.propertyOf(object));
   * // => [true, 'fred']
   *
   * var object = { 'a': 3, 'b': 1, 'c': 2 };
   * _.sortBy(['a', 'b', 'c'], _.propertyOf(object));
   * // => ['b', 'c', 'a']
   */
  function propertyOf(object) {
    return function(key) {
      return object == null ? undefined : object[key];
    };
  }

  return propertyOf;
});