2 var isObject = require('./_is-object')
3 , getPrototypeOf = require('./_object-gpo')
4 , HAS_INSTANCE = require('./_wks')('hasInstance')
5 , FunctionProto = Function.prototype;
6 // 19.2.3.6 Function.prototype[@@hasInstance](V)
7 if(!(HAS_INSTANCE in FunctionProto))require('./_object-dp').f(FunctionProto, HAS_INSTANCE, {value: function(O){
8 if(typeof this != 'function' || !isObject(O))return false;
9 if(!isObject(this.prototype))return O instanceof this;
10 // for environment w/o native `@@hasInstance` logic enough `instanceof`, but add this:
11 while(O = getPrototypeOf(O))if(this.prototype === O)return true;