invertBy.js (1651B)
1 var baseIteratee = require('./_baseIteratee'), 2 createInverter = require('./_createInverter'); 3 4 /** Used for built-in method references. */ 5 var objectProto = Object.prototype; 6 7 /** Used to check objects for own properties. */ 8 var hasOwnProperty = objectProto.hasOwnProperty; 9 10 /** 11 * Used to resolve the 12 * [`toStringTag`](http://ecma-international.org/ecma-262/7.0/#sec-object.prototype.tostring) 13 * of values. 14 */ 15 var nativeObjectToString = objectProto.toString; 16 17 /** 18 * This method is like `_.invert` except that the inverted object is generated 19 * from the results of running each element of `object` thru `iteratee`. The 20 * corresponding inverted value of each inverted key is an array of keys 21 * responsible for generating the inverted value. The iteratee is invoked 22 * with one argument: (value). 23 * 24 * @static 25 * @memberOf _ 26 * @since 4.1.0 27 * @category Object 28 * @param {Object} object The object to invert. 29 * @param {Function} [iteratee=_.identity] The iteratee invoked per element. 30 * @returns {Object} Returns the new inverted object. 31 * @example 32 * 33 * var object = { 'a': 1, 'b': 2, 'c': 1 }; 34 * 35 * _.invertBy(object); 36 * // => { '1': ['a', 'c'], '2': ['b'] } 37 * 38 * _.invertBy(object, function(value) { 39 * return 'group' + value; 40 * }); 41 * // => { 'group1': ['a', 'c'], 'group2': ['b'] } 42 */ 43 var invertBy = createInverter(function(result, value, key) { 44 if (value != null && 45 typeof value.toString != 'function') { 46 value = nativeObjectToString.call(value); 47 } 48 49 if (hasOwnProperty.call(result, value)) { 50 result[value].push(key); 51 } else { 52 result[value] = [key]; 53 } 54 }, baseIteratee); 55 56 module.exports = invertBy;