[RESOLVED] Try catch for checking element

[code?]

Okay, so here's the deal. I have a function that runs through a for loop, and picks elements and adds them to an array. I don't want to add an element that's not there, so I want to set up a try catch so that it can catch an error and hopefully return when it's trying to get an id that's not there.

How do I check if the generated element id is valid?
Or is there someway I can get the last child in a node, regardless of id?

<div id="mainDiv">
    <div id="subDiv1"></div>
    <div id="subDiv2"></div>
    <div id="subDiv3"></div>
    <div id="subDiv4"></div>
    <div id="subDiv5"></div>
</div>

Here is some sample code.

function getElements()
{
    var elemArray = new array();
    for (var i = 1; i < 9; i++)
    {
        var elem = document.getElementById("subDiv" + i);
        elemArray[i - 1] = elem;
    }
}