| 'use strict'; |
| var isObject = require('../internals/is-object'); |
| var definePropertyModule = require('../internals/object-define-property'); |
| var getPrototypeOf = require('../internals/object-get-prototype-of'); |
| var wellKnownSymbol = require('../internals/well-known-symbol'); |
| |
| var HAS_INSTANCE = wellKnownSymbol('hasInstance'); |
| var FunctionPrototype = Function.prototype; |
| |
| // `Function.prototype[@@hasInstance]` method |
| // https://tc39.github.io/ecma262/#sec-function.prototype-@@hasinstance |
| if (!(HAS_INSTANCE in FunctionPrototype)) { |
| definePropertyModule.f(FunctionPrototype, HAS_INSTANCE, { value: function (O) { |
| if (typeof this != 'function' || !isObject(O)) return false; |
| if (!isObject(this.prototype)) return O instanceof this; |
| // for environment w/o native `@@hasInstance` logic enough `instanceof`, but add this: |
| while (O = getPrototypeOf(O)) if (this.prototype === O) return true; |
| return false; |
| } }); |
| } |