while_each.js (2442B)
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 * While a test condition is true, invokes a function once for each element in a collection. 31 * 32 * @param {Collection} collection - input collection 33 * @param {Function} predicate - function which indicates whether to continue iterating over a collection 34 * @param {Function} fcn - function to invoke 35 * @param {*} [thisArg] - execution context for the applied function 36 * @throws {TypeError} first argument must be a collection 37 * @throws {TypeError} second argument must be a function 38 * @throws {TypeError} third argument must be a function 39 * @returns {Collection} input collection 40 * 41 * @example 42 * function predicate( v, index, collection ) { 43 * return ( v === v ); 44 * } 45 * 46 * function log( v, index, collection ) { 47 * console.log( '%s: %d', index, v ); 48 * } 49 * 50 * var arr = [ 1, 2, 3, 4, NaN, 5 ]; 51 * 52 * whileEach( arr, predicate, log ); 53 */ 54 function whileEach( collection, predicate, fcn, thisArg ) { 55 var len; 56 var i; 57 if ( !isCollection( collection ) ) { 58 throw new TypeError( 'invalid argument. First argument must be a collection. Value: `'+collection+'`.' ); 59 } 60 if ( !isFunction( predicate ) ) { 61 throw new TypeError( 'invalid argument. Second argument must be a function. Value: `'+predicate+'`.' ); 62 } 63 if ( !isFunction( fcn ) ) { 64 throw new TypeError( 'invalid argument. Third argument must be a function. Value: `'+fcn+'`.' ); 65 } 66 len = collection.length; 67 i = 0; 68 while ( 69 i < len && 70 predicate( collection[ i ], i, collection ) 71 ) { 72 fcn.call( thisArg, collection[ i ], i, collection ); 73 i += 1; 74 len = collection.length; // ...account for dynamically resizing a collection 75 } 76 return collection; 77 } 78 79 80 // EXPORTS // 81 82 module.exports = whileEach;