Version 1.x

This is a utility function that facilitates a delegation from one object to another bypassing a constructor. It is used inside dcl and exposed because it is frequently required by user’s code.

Description

It creates an empty object with a desired prototypal inheritance. All missing properties will be delegated.

The best way to describe dcl.delegate() is to give its definition:

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function F(){} // private empty constructor function

dcl.delegate = function(o){
  // assigning the object as a prototype to an empty function
  F.prototype = o;
  // creating new empty object with a desired prototype
  var t = new F;
  // cleaning up our prototype to prevent a memory leak
  F.prototype = null;
  // return our object
  return t;
};

Examples

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var x = dcl.delegate({a: 1, b: 2});

console.log(x.a); // 1
console.log(x.b); // 2
console.log(x.c); // undefined

x.a = 42;
console.log(x.a); // 42

delete x.a;
console.log(x.a); // 1

x.c = "hello!";
console.log(x.c); // hello!

delete x.c;
console.log(x.c); // undefined

Notes

dcl.delegate() is a first half of Object.create(), which is defined in ECMAScript 5, and supported by all modern browsers. Unfortunately IE supports it starting from IE9, so dcl carries this manual implementation to support previous IE browsers.