shift_object.js (1329B)
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 // MAIN // 22 23 /** 24 * Removes and returns the first element of an array-like object. 25 * 26 * @private 27 * @param {Object} obj - input array-like object 28 * @returns {Array} input object and the removed element 29 * 30 * @example 31 * var obj = { 32 * 'length': 2, 33 * '0': 1.0, 34 * '1': 2.0 35 * }; 36 * 37 * var out = shift( obj ); 38 * // returns [ { 'length': 1, '0': 2.0 }, 1.0 ] 39 */ 40 function shift( obj ) { 41 var len; 42 var v; 43 var i; 44 if ( obj.length === 0 ) { 45 return [ obj, void 0 ]; 46 } 47 len = obj.length - 1; 48 v = obj[ 0 ]; 49 50 // Shift all elements down... 51 for ( i = 0; i < len; i++ ) { 52 obj[ i ] = obj[ i+1 ]; 53 } 54 delete obj[ len ]; 55 obj.length = len; 56 return [ obj, v ]; 57 } 58 59 60 // EXPORTS // 61 62 module.exports = shift;