| 'use strict'; | 
| var aSet = require('../internals/a-set'); | 
| var SetHelpers = require('../internals/set-helpers'); | 
| var clone = require('../internals/set-clone'); | 
| var size = require('../internals/set-size'); | 
| var getSetRecord = require('../internals/get-set-record'); | 
| var iterateSet = require('../internals/set-iterate'); | 
| var iterateSimple = require('../internals/iterate-simple'); | 
|   | 
| var has = SetHelpers.has; | 
| var remove = SetHelpers.remove; | 
|   | 
| // `Set.prototype.difference` method | 
| // https://github.com/tc39/proposal-set-methods | 
| module.exports = function difference(other) { | 
|   var O = aSet(this); | 
|   var otherRec = getSetRecord(other); | 
|   var result = clone(O); | 
|   if (size(O) <= otherRec.size) iterateSet(O, function (e) { | 
|     if (otherRec.includes(e)) remove(result, e); | 
|   }); | 
|   else iterateSimple(otherRec.getIterator(), function (e) { | 
|     if (has(O, e)) remove(result, e); | 
|   }); | 
|   return result; | 
| }; |