JavaScript inheritance and the constructor property

Question

Consider the following code.

function a() {}
function b() {}
function c() {}

b.prototype = new a();
c.prototype = new b();

console.log((new a()).constructo         


        

Answer 1

By default,

function b() {}

then b.prototype has a .constructor property which is set to b automatically. However, you're currently overwriting the prototype and thus discarding that variable:

b.prototype = new a;

Then b.prototype does not have a .constructor property anymore; it was erased with the overwrite. It does inherit from a though, and (new a).constructor === a, and hence (new b).constructor === a (it is referring to the same property in the prototype chain).

Best to do is to simply setting it manually afterwards:

b.prototype.constructor = b;

You could also make a little function for this:

function inherit(what, from) {
    what.prototype = new from;
    what.prototype.constructor = what;
}

http://jsfiddle.net/79xTg/5/