video.js/src/js/utils/obj.js

/**
 * @file obj.js
 * @module obj
 */

/**
 * @callback obj:EachCallback
 *
 * @param {Mixed} value
 *        The current key for the object that is being iterated over.
 *
 * @param {string} key
 *        The current key-value for object that is being iterated over
 */

/**
 * @callback obj:ReduceCallback
 *
 * @param {Mixed} accum
 *        The value that is accumulating over the reduce loop.
 *
 * @param {Mixed} value
 *        The current key for the object that is being iterated over.
 *
 * @param {string} key
 *        The current key-value for object that is being iterated over
 *
 * @return {Mixed}
 *         The new accumulated value.
 */

/**
 * Array-like iteration for objects.
 *
 * @param {Object} object
 *        The object to iterate over
 *
 * @param {obj:EachCallback} fn
 *        The callback function which is called for each key in the object.
 */
export function each(object, fn) {
  Object.keys(object).forEach(key => fn(object[key], key));
}

/**
 * Array-like reduce for objects.
 *
 * @param {Object} object
 *        The Object that you want to reduce.
 *
 * @param {Function} fn
 *         A callback function which is called for each key in the object. It
 *         receives the accumulated value and the per-iteration value and key
 *         as arguments.
 *
 * @param {Mixed} [initial = 0]
 *        Starting value
 *
 * @return {Mixed}
 *         The final accumulated value.
 */
export function reduce(object, fn, initial = 0) {
  return Object.keys(object).reduce(
    (accum, key) => fn(accum, object[key], key), initial);
}