lowercase_keys.js (1392B)
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 hasOwnProp = require( '@stdlib/assert/has-own-property' ); 24 25 26 // MAIN // 27 28 /** 29 * Converts each object key to lowercase. 30 * 31 * @param {Object} obj - source object 32 * @throws {TypeError} must provide an object 33 * @returns {Object} new object 34 * 35 * @example 36 * var obj1 = { 37 * 'A': 1, 38 * 'B': 2 39 * }; 40 * 41 * var obj2 = lowercaseKeys( obj1 ); 42 * // returns { 'a': 1, 'b': 2 } 43 */ 44 function lowercaseKeys( obj ) { 45 var out; 46 var key; 47 if ( typeof obj !== 'object' || obj === null ) { 48 throw new TypeError( 'invalid argument. Must provide an object. Value: `'+obj+'`.' ); 49 } 50 out = {}; 51 for ( key in obj ) { 52 if ( hasOwnProp( obj, key ) ) { 53 out[ key.toLowerCase() ] = obj[ key ]; 54 } 55 } 56 return out; 57 } 58 59 60 // EXPORTS // 61 62 module.exports = lowercaseKeys;