time-to-botec

Benchmark sampling in different programming languages
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pick_by.js (1900B)

      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 objectKeys = require( './../../keys' );
     24 var isFunction = require( '@stdlib/assert/is-function' );
     25 
     26 
     27 // MAIN //
     28 
     29 /**
     30 * Returns a partial object copy containing properties for which a predicate returns a truthy value.
     31 *
     32 * @param {Object} obj - source object
     33 * @param {Function} predicate - predicate function
     34 * @throws {TypeError} first argument must be an object
     35 * @throws {TypeError} second argument must be a function
     36 * @returns {Object} new object
     37 *
     38 * @example
     39 * function predicate( key, value ) {
     40 *     return ( value > 1 );
     41 * }
     42 *
     43 * var obj1 = {
     44 *     'a': 1,
     45 *     'b': 2
     46 * };
     47 *
     48 * var obj2 = pickBy( obj1, predicate );
     49 * // returns { 'b': 2 }
     50 */
     51 function pickBy( obj, predicate ) {
     52 	var keys;
     53 	var out;
     54 	var key;
     55 	var i;
     56 	if ( typeof obj !== 'object' || obj === null ) {
     57 		throw new TypeError( 'invalid argument. First argument must be an object. Value: `'+obj+'`.' );
     58 	}
     59 	if ( !isFunction( predicate ) ) {
     60 		throw new TypeError( 'invalid argument. Second argument must be a function. Value: `'+predicate+'`.' );
     61 	}
     62 	out = {};
     63 	keys = objectKeys( obj );
     64 	for ( i = 0; i < keys.length; i++ ) {
     65 		key = keys[ i ];
     66 		if ( predicate( key, obj[ key ] ) ) {
     67 			out[ key ] = obj[ key ];
     68 		}
     69 	}
     70 	return out;
     71 }
     72 
     73 
     74 // EXPORTS //
     75 
     76 module.exports = pickBy;