collection/forEach.js

import arrayEach from '../internal/arrayEach';
import baseEach from '../internal/baseEach';
import bindCallback from '../internal/bindCallback';
import isArray from '../lang/isArray';

/**
 * Iterates over elements of `collection` invoking `iteratee` for each element.
 * The `iteratee` is bound to `thisArg` and invoked with three arguments;
 * (value, index|key, collection). Iterator functions may exit iteration early
 * by explicitly returning `false`.
 *
 * **Note:** As with other "Collections" methods, objects with a `length` property
 * are iterated like arrays. To avoid this behavior `_.forIn` or `_.forOwn`
 * may be used for object iteration.
 *
 * @static
 * @memberOf _
 * @alias each
 * @category Collection
 * @param {Array|Object|string} collection The collection to iterate over.
 * @param {Function} [iteratee=_.identity] The function invoked per iteration.
 * @param {*} [thisArg] The `this` binding of `iteratee`.
 * @returns {Array|Object|string} Returns `collection`.
 * @example
 *
 * _([1, 2, 3]).forEach(function(n) { console.log(n); });
 * // => logs each value from left to right and returns the array
 *
 * _.forEach({ 'one': 1, 'two': 2, 'three': 3 }, function(n, key) { console.log(n, key); });
 * // => logs each value-key pair and returns the object (iteration order is not guaranteed)
 */
function forEach(collection, iteratee, thisArg) {
  return (typeof iteratee == 'function' && typeof thisArg == 'undefined' && isArray(collection))
    ? arrayEach(collection, iteratee)
    : baseEach(collection, bindCallback(iteratee, thisArg, 3));
}

export default forEach;