65 lines
1.4 KiB
JavaScript
65 lines
1.4 KiB
JavaScript
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/**
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* @license Apache-2.0
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*
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* Copyright (c) 2018 The Stdlib Authors.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict';
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// MAIN //
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/**
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* Adds one or more elements to the beginning of an array-like object.
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*
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* @private
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* @param {Object} obj - input array-like object
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* @param {Array} items - items to add
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* @returns {Object} input object
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*
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* @example
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* var obj = {
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* 'length': 2,
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* '0': 1.0,
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* '1': 2.0
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* };
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*
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* obj = unshift( obj, [ 3.0, 4.0 ] );
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* // returns { 'length': 4, '0': 3.0, '1': 4.0, '2': 1.0, '3': 2.0 }
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*/
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function unshift( obj, items ) {
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var len;
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var n;
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var i;
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len = obj.length;
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n = items.length;
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// Shift all existing elements to the right...
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for ( i = len-1; i >= 0; i-- ) {
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obj[ i+n ] = obj[ i ];
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}
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// Add new elements...
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for ( i = 0; i < n; i++ ) {
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obj[ i ] = items[ i ];
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}
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obj.length = len + n;
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return obj;
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}
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// EXPORTS //
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module.exports = unshift;
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