(javascript) getting a div's height

[msimmons]

I have a div that will have a dynamic height. It will only vary on page load but will be different from time to time so I cannot hard code the height (need to know the height in a different function). Here is what I tried:

var temptest = getElementById('content').style.height;
alert(temptest);

this gives me the 'object expected' error...

any hints?
Michael