| 'use strict'; | 
| var $ = require('../internals/export'); | 
| var getBuiltIn = require('../internals/get-built-in'); | 
| var uncurryThis = require('../internals/function-uncurry-this'); | 
| var aCallable = require('../internals/a-callable'); | 
| var requireObjectCoercible = require('../internals/require-object-coercible'); | 
| var toPropertyKey = require('../internals/to-property-key'); | 
| var iterate = require('../internals/iterate'); | 
| var fails = require('../internals/fails'); | 
|   | 
| // eslint-disable-next-line es/no-object-groupby -- testing | 
| var nativeGroupBy = Object.groupBy; | 
| var create = getBuiltIn('Object', 'create'); | 
| var push = uncurryThis([].push); | 
|   | 
| var DOES_NOT_WORK_WITH_PRIMITIVES = !nativeGroupBy || fails(function () { | 
|   return nativeGroupBy('ab', function (it) { | 
|     return it; | 
|   }).a.length !== 1; | 
| }); | 
|   | 
| // `Object.groupBy` method | 
| // https://tc39.es/ecma262/#sec-object.groupby | 
| $({ target: 'Object', stat: true, forced: DOES_NOT_WORK_WITH_PRIMITIVES }, { | 
|   groupBy: function groupBy(items, callbackfn) { | 
|     requireObjectCoercible(items); | 
|     aCallable(callbackfn); | 
|     var obj = create(null); | 
|     var k = 0; | 
|     iterate(items, function (value) { | 
|       var key = toPropertyKey(callbackfn(value, k++)); | 
|       // in some IE versions, `hasOwnProperty` returns incorrect result on integer keys | 
|       // but since it's a `null` prototype object, we can safely use `in` | 
|       if (key in obj) push(obj[key], value); | 
|       else obj[key] = [value]; | 
|     }); | 
|     return obj; | 
|   } | 
| }); |