'use strict'; var isCallable = require('../internals/is-callable'); 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.es/ecma262/#sec-function.prototype-@@hasinstance if (!(HAS_INSTANCE in FunctionPrototype)) { definePropertyModule.f(FunctionPrototype, HAS_INSTANCE, { value: function (O) { if (!isCallable(this) || !isObject(O)) return false; var P = this.prototype; if (!isObject(P)) return O instanceof this; // for environment w/o native `@@hasInstance` logic enough `instanceof`, but add this: while (O = getPrototypeOf(O)) if (P === O) return true; return false; } }); }