Question

This has been driving me crazy because I can’t find anything on Google. Maybe it’s because I don’t know the right terminology to search right. But this is what I’m trying to do.

I want to create a function that acts like an object. I’m think it’s called a method, though I could be wrong.

Check this out, this is some pseudocode of what I would like it to do.

function myMethod(){
var p = this.getAttribute('x');
var p = p+1;
return p;
}

function otherFunction(){
var q = document.getElementByID('Element').myMethod();
alert(q);
}

So, I can’t get this to work. It keeps saying myMethod() is undefined and not a function.

Answer 1

If you want myMethod to be available on elements, you’d have to append it to elements’ prototype.

Element.prototype.myMethod = myMethod;

The concept of prototype is big, but it comes down to the fact that instances of functions have a function available in the way that you describe as ‘like an object’.

In this case, any element on the page is an instance of the Element function. Therefore, any element will have .myMethod available, which you can call. (Element is a function although you don’t really deal with that – the instances are available because you put them there in HTML, so you bypass using Element.)

Second, if you have var p, then another var p does not make much sense. Just use p = p + 1, or p++ (shortcut for adding one).