Javascript Array Dealing with .length

[Judson]

Say I have this looping for statement "And it works fine":

for (i=1; i<10; i++) {
obj = document.getElementById("rTable" + i);
if (obj == null) break;
if (obj.offsetHeight >= 268) {
obj.style.height="268px";
}
}

The problem is that I don't want to use i<10; because I don't know the exact
number.
I want to use the length of the array. So how do I set that up?

Thanks,

Judd