104 lines
2.3 KiB
JavaScript
104 lines
2.3 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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// MODULES //
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var isArray = require( '@stdlib/assert/is-array' );
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var copy = require( './../../copy' );
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var hasOwnProp = require( '@stdlib/assert/has-own-property' );
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var defaults = require( './defaults.json' );
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var validate = require( './validate.js' );
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// MAIN //
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/**
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* Extracts a property value from each element of an object array.
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*
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* @param {Array} arr - source array
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* @param {*} prop - property to access
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* @param {Options} [options] - function options
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* @param {boolean} [options.copy=true] - boolean indicating whether to return a new data structure
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* @throws {TypeError} first argument must be an object array
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* @throws {TypeError} options argument must be an object
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* @throws {TypeError} must provide valid options
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* @returns {Array} destination array
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*
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* @example
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* var arr = [
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* { 'a': 1, 'b': 2 },
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* { 'a': 0.5, 'b': 3 }
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* ];
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*
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* var out = pluck( arr, 'a' );
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* // returns [ 1, 0.5 ]
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*
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* @example
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* var arr = [
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* { 'a': 1, 'b': 2 },
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* { 'a': 0.5, 'b': 3 }
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* ];
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*
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* var out = pluck( arr, 'a', {'copy':false} );
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* // returns [ 1, 0.5 ]
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*
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* var bool = ( arr[ 0 ] === out[ 0 ] );
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* // returns true
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*/
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function pluck( arr, prop, options ) {
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var opts;
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var out;
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var err;
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var v;
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var i;
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if ( !isArray( arr ) ) {
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throw new TypeError( 'invalid argument. First argument must be an array. Value: `' + arr + '`.' );
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}
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opts = copy( defaults );
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if ( arguments.length > 2 ) {
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err = validate( opts, options );
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if ( err ) {
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throw err;
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}
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}
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if ( opts.copy ) {
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out = new Array( arr.length );
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} else {
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out = arr;
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}
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for ( i = 0; i < arr.length; i++ ) {
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v = arr[ i ];
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if (
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v !== void 0 &&
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v !== null &&
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hasOwnProp( v, prop )
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) {
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out[ i ] = v[ prop ];
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}
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}
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return out;
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}
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// EXPORTS //
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module.exports = pluck;
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