Question

ok so i know that prototype is used for inheritance and when coupled with a constructor function can be used to make custom methods. so my question here is two fold: how do i make methods for pre-built JavaScript objects like integers,strings,arrays,etc…

the other question is besides making my own methods what is the usefulness of constructors/prototype in everyday web development(i.e. creating websites) or is this more so for high-end development like making a web app or developing with new tech(i.e. html5 canvas or three.js) i haven’t seen an example anywhere on the web of this being used in an everyday situation.

Answer 1

To create a Javascript method to an already existing object, you can simple add it to its constructor’s prototype:

String.prototype.firstLetter = function() { return this.charAt(0); }
var myStr = "Cool str!";
alert(myStr.firstLetter()); // 'C'

As for how useful it will be, depends on what you do with Javascript. If you write client-side code and you need to modify an existing component, monkey-patching a function may be useful there. If you need some structure on your code (and you do), creating an object to represent the interface state may be useful.

Also, knowing how to use a tool usually avoids self-harm. =)

If you are interested, you may want to take a look into Crockford’s page or buy his Javascript: The Good Parts book.

There is a lot of confusion you can avoid if you get to know the language, and you may even get to like it and find out you can do a lot of useful stuff in it.