prototype and constructor object properties

Question

I\'ve:

function Obj1(param)
{
    this.test1 = param || 1;

}

function Obj2(param, par)
{
    this.test2 = param;

}

now when I do:

<

Answer 1

Well, the constructor property is a property like any other, on the prototype (property) of Obj1. If you understand how prototypes work, this might help:

>>> obj.hasOwnProperty("constructor")
false

// obj's [[Prototype]] is Obj2.prototype
>>> Obj2.prototype.hasOwnProperty("constructor")
false

// Obj2.prototype's [[Prototype]] is Obj1.prototype
>>> Obj1.prototype.hasOwnProperty("constructor")
true

// Oh?
>>> Obj1.prototype.constructor
Obj1()

Aha! So obj has no constructor, JS goes to get it up the [[Prototype]] chain, all the way from Obj1.prototype.constructor

I'm not sure why the constructor property isn't just set on an object when you use `new'. There might be a reason, or it might just be an oversight. Either way, I tend to avoid it.