Question

I am using javascript to display the height of my current div.

This is an example of the effected area

//css
.test
{
height:1px;
}

#test1
{
margin:1px;
}

//html
<div id="test1" class="test"></div>

//javascript
var a = document.getElementById('test1');

a.style.height //how I access the style

Firebug says that the length of style is 0 and height is empty.
How can I access the correct height?

Answer 1

You need to look at the computed style, not the specified style. See Quirks mode’s getstyle page which answers the question

Sometimes you’ll want to see what styles the default document view has. For instance, you gave a paragraph an width of 50%, but how do you see how many pixels that is in your users’ browser?

and it explains how to derive and use the getstyle function, though it’s easier to use a library like jquery which provides a simple css function.