Convention for prototype inheritance in JavaScript

Question

I see a lot of code like this:

function Base() {}
function Sub() {}
Sub.prototype = new Base();

However, if you do:

s = new         


        

Answer 1

Yeah,

Sub.prototype.constructor = Sub;

let's you use instanceof but there's a better solution. Look here: ,TDD JS Inheritance on GitHub ,and find the Parasitic Combination Inheritance pattern. The code is TDD'd so you should be able to grok it very quickly and then simply change the names to get you started. This is basically what YAHOO.lang.extend uses (source: yahoo employee and author Nicholas Zakas's Professional JavaScript for Web Developer's, 2nd ED, page 181). Good book by the way (not affiliated in any way!)

Why? Because the classical pattern you're working with has staticy reference vars (if you create var arr = [1,2] in the base object, ALL instances will have read/write and will "share state" of 'arr'! If you use constructor stealing you can get around this. See my examples.