keyOf.js.flow

/**
 * Copyright (c) 2013-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 *
 * @providesModule keyOf
 */

/**
 * Allows extraction of a minified key. Let's the build system minify keys
 * without losing the ability to dynamically use key strings as values
 * themselves. Pass in an object with a single key/val pair and it will return
 * you the string key of that single record. Suppose you want to grab the
 * value for a key 'className' inside of an object. Key/val minification may
 * have aliased that key to be 'xa12'. keyOf({className: null}) will return
 * 'xa12' in that case. Resolve keys you want to use once at startup time, then
 * reuse those resolutions.
 */
var keyOf = function (oneKeyObj) {
  var key;

  for (key in oneKeyObj) {
    if (!oneKeyObj.hasOwnProperty(key)) {
      continue;
    }

    return key;
  }

  return null;
};

module.exports = keyOf;