How do I select specific dynamic form element in JavaScript

[Pailin]

In particular an <img>, which I don't think is considered an element, as if I do:

var el = document.frmSuppMessage.elements;
for(var i = 0 ; i < el.length ; ++i) {
alert("El name ="+ el[i].name +".");
}

<img ...> tags do not show up?

so I can't go through all elements and do a compare as I've done in the past :/

Main point:

The tag in question:

<img SRC="../images/+.gif" name="img<%=rsOrd.Fields("Part_No")%>" onclick="this.src=hideRows('<%=rsOrd.Fields("Part_No")%>')">

if I specify the exact name:
alert("this="+ document.imgECL250.src + ".");

gets me:
this=http://SERVER/SITE/images/+.gif

What I want to do is something like:

function hideRows(rowIDs)
{
var imgToMod;
imgToMod = "Buy" + rowIDs

alert("this="+ document.imgToMod.src + ".");
}

which of course gets me:
Error:'document.imgToMod.src' is null or not an object

But I think you get what I'm trying to do...

I can think of some sloppy hidden text input ways round this problem, but would love to know the smart way.

Cheers, Pailin