es6.function.has-instance.js 655 B

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  1. 'use strict';
  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;
  12. return false;
  13. }});