debian-mirror-gitlab/core-js/modules/es.function.has-instance.js
2019-09-25 13:30:05 +05:30

20 lines
933 B
JavaScript

'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;
} });
}