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javascriptprototypeprototypal-inheritance

How to access object prototype in javascript?

In all the articles it is written that JavaScript is a prototype-based language, meaning that every object has a prototype (or, more precisely, prototype chain).

So far, I've tried the following code snippet:

var F = function();
F.prototype.member1 = 1;
var object1 = new F();
console.log(object1.member1); // prints 1

How can I access the prototype object of object1? Is there a browser-neutral way to do that (I mean, not relying on __proto__ property? Seen this link, but maybe there are new developments since 2010) If I can't, could you share please the rationale behind the hood?

Solution 
  • var f = function();
var instance = new f();

    If you know name of instance class function, you can simply access prototype as:

    var prototype = f.prototype;
prototype.someMember = someValue;

    If you don't:

    1)

    var prototype = Object.getPrototypeOf(instance);
prototype.someMember = someValue;

    2) or

    var prototype = instance.__proto__;
prototype.someMember = someValue;

    3) or

    var prototype = instance.constructor.prototype; // works only if constructor is properly assigned and not modified
prototype.someMember = someValue;

    For compatibility you can place into your code the following snippet (and use always Object.getPrototypeOf(instance) to return prototype):

    if(!Object.getPrototypeOf) {

  if(({}).__proto__ === Object.prototype && ([]).__proto__ === Array.prototype) {

    Object.getPrototypeOf = function getPrototypeOf(object) {
      return object.__proto__;
    };

  } else {

    Object.getPrototypeOf = function getPrototypeOf(object) {

      // May break if the constructor has been changed or removed
      return object.constructor ? object.constructor.prototype : void 0;

    };

  }
}

    UPDATE:

    According to ECMA-262 6th Edition (June 2015) __proto__ property is standardized as additional feature for Web browsers. All latest editions of top browsers supports it now. Read more about __proto__: