Undefined height

I have two divisions (menu and content). content's height is undefined so that it can expand. I wanted the menu 开发者_StackOverflowto have the height of the "expanded" content.

I actually understood how to do it with offset.Height, but the height is undefined.

Is there any way I could find the height of the expanded division?

Using jQuery you can do

$('#content').height(); //Assuming div content have id="content"

jQuery has a nice method for getting the height of an element, with examples here: http://api.jquery.com/height/