Easy questions about if() and getElementById

[WFTomba]

Please forgive my ignorance. I've read a lot of reference and instructional materials but I need a couple of basic things clarified.

Suppose, in JavaScript, I do like so:

var a,b;
a=document.getElementById("element");
if(a){b= // . . . et cetera

I have seen people do things like this. My two questions:

1. What exactly does the variable a get filled with in line 2? It supposedly becomes a "reference" to the object with the specified ID, but what form does this "reference" take, specifically?

2. What's the purpose of the if() statement in the third line?

Thank you.

[Dormilich]

1. a holds an object (which in this case is an HTMLElement object)
2. the if statement checks whether the allocation of line 2 was successful, that is if a holds the element object or not (ie. there was no element having an id="element")

if (a) is true for any value of a besides null, 0, false and '' (empty string)

regards

note: try this:

alert(a);