firstElementChild doesn't work in Internet Explorer 7...what are my options?

Question

Consider the JavaScript below:

var v;
if (this.children.length > 0) {
    v = this.firstElementChild.value;
}

This works in modern versions of FireFox and Chrome but this.firstElementChild.value throws an exception in Internet Explorer 7-8. Is there another way for me to get this to work for all browsers?

UPDATE -- FINAL SOLUTION

I went with the following:

v = (this.firstElementChild || this.children[0] || {}).value --Thanks to all.

Answer 1

this.firstElementChild should work in every significant browser bar IE <=9 and Firefox 3 (QuirksMode).

this.children[0] will work in every significant browser bar Firefox 3, except that IE <=9 counts comment nodes as element nodes (QuirksMode). This may or may not be an issue for you.

The catch-all system is this:

var node = this.firstChild,
    firstElementChild = null;

for ( ; node; node = node.nextSibling) {
    if (node.nodeType === 1) {
        firstElementChild = node;
        break;
    }
}

firstElementChild will then be the first element child if one exists, null otherwise. It would be best to see if this.firstElementChild exists before doing the loop, for performance reasons.