prepend.js (2879B)
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 isArray = require( '@stdlib/assert/is-array' ); 24 var isCollection = require( '@stdlib/assert/is-collection' ); 25 var isTypedArrayLike = require( '@stdlib/assert/is-typed-array-like' ); 26 var isInteger = require( '@stdlib/assert/is-integer' ); 27 var prependArray = require( './prepend_array.js' ); 28 var prependObject = require( './prepend_object.js' ); 29 var prependTypedArray = require( './prepend_typed_array.js' ); 30 31 32 // MAIN // 33 34 /** 35 * Adds elements from one collection to the beginning of another collection. 36 * 37 * @param {Collection} collection1 - collection 38 * @param {Collection} collection2 - collection containing elements to add 39 * @throws {TypeError} first argument must be either an array, typed array, or an array-like object 40 * @throws {TypeError} second argument must be an array-like object 41 * @returns {Collection} updated collection 42 * 43 * @example 44 * var arr = [ 1.0, 2.0, 3.0, 4.0, 5.0 ]; 45 * 46 * arr = prepend( arr, [ 6.0, 7.0 ] ); 47 * // returns [ 6.0, 7.0, 1.0, 2.0, 3.0, 4.0, 5.0 ] 48 * 49 * @example 50 * var Float64Array = require( '@stdlib/array/float64' ); 51 * 52 * var arr = new Float64Array( [ 1.0, 2.0, 3.0, 4.0, 5.0 ] ); 53 * // returns <Float64Array>[ 1.0, 2.0, 3.0, 4.0, 5.0 ] 54 * 55 * arr = prepend( arr, [ 6.0, 7.0 ] ); 56 * // returns <Float64Array>[ 6.0, 7.0, 1.0, 2.0, 3.0, 4.0, 5.0 ] 57 */ 58 function prepend( collection1, collection2 ) { 59 if ( !isCollection( collection2 ) ) { 60 throw new TypeError( 'invalid argument. Second argument must be an array-like object. Value: `'+collection2+'`.' ); 61 } 62 if ( isArray( collection1 ) ) { 63 return prependArray( collection1, collection2 ); 64 } 65 // Check for a typed-array-like object, as verifying actual typed arrays is expensive... 66 if ( isTypedArrayLike( collection1 ) ) { 67 return prependTypedArray( collection1, collection2 ); 68 } 69 // Check for an array-like object... 70 if ( 71 collection1 !== null && 72 typeof collection1 === 'object' && 73 typeof collection1.length === 'number' && 74 isInteger( collection1.length ) && 75 collection1.length >= 0 76 ) { 77 return prependObject( collection1, collection2 ); 78 } 79 throw new TypeError( 'invalid argument. First argument must be either an Array, Typed Array, or an array-like Object. Value: `'+collection1+'`.' ); 80 } 81 82 83 // EXPORTS // 84 85 module.exports = prepend;