for_each.js (1907B)
1 /** 2 * @license Apache-2.0 3 * 4 * Copyright (c) 2018 The Stdlib Authors. 5 * 6 * Licensed under the Apache License, Version 2.0 (the "License"); 7 * you may not use this file except in compliance with the License. 8 * You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, software 13 * distributed under the License is distributed on an "AS IS" BASIS, 14 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 15 * See the License for the specific language governing permissions and 16 * limitations under the License. 17 */ 18 19 'use strict'; 20 21 // MODULES // 22 23 var isCollection = require( '@stdlib/assert/is-collection' ); 24 var isFunction = require( '@stdlib/assert/is-function' ); 25 26 27 // MAIN // 28 29 /** 30 * Invokes a function once for each element in a collection. 31 * 32 * @param {Collection} collection - input collection 33 * @param {Function} fcn - function to invoke 34 * @param {*} [thisArg] - execution context 35 * @throws {TypeError} first argument must be a collection 36 * @throws {TypeError} second argument must be a function 37 * @returns {Collection} input collection 38 * 39 * @example 40 * function log( v, index, collection ) { 41 * console.log( '%s: %d', index, v ); 42 * } 43 * 44 * var arr = [ 1, 2, 3, 4 ]; 45 * 46 * forEach( arr, log ); 47 */ 48 function forEach( collection, fcn, thisArg ) { 49 var len; 50 var i; 51 if ( !isCollection( collection ) ) { 52 throw new TypeError( 'invalid argument. First argument must be a collection. Value: `'+collection+'`.' ); 53 } 54 if ( !isFunction( fcn ) ) { 55 throw new TypeError( 'invalid argument. Second argument must be a function. Value: `'+fcn+'`.' ); 56 } 57 len = collection.length; 58 for ( i = 0; i < len; i++ ) { 59 fcn.call( thisArg, collection[ i ], i, collection ); 60 61 // Account for dynamically resizing a collection: 62 len = collection.length; 63 } 64 return collection; 65 } 66 67 68 // EXPORTS // 69 70 module.exports = forEach;