Question

Specifically, a class or id within the css.

Would you use something similar to $(window).height()?

Answer 1

It’s not clear exactly what you want, but as a general rule all the styles applied to a given element can be accessed in JavaScript using something like:

element.style.<property-name>

So using native JavaScript you can do:

var elemStyles = document.getElementById("someId").style;
var styleWidth = elemStyles.width;

Assuming at least one element with a given CSS class and a framework that can select elements by class, you can similarly do:

var elemStyles = $(".someClass")[0].style;
var styleWidth = elemStyles.width;

Or depending upon what (if any) JavaScript framework you are using, there may be specialized methods that you can use to access/inspect various CSS attributes for a given element.

Note that any of these methods will bring back all the styles applied to the element, whether they are coming from the CSS file, from inline CSS declarations, or added programmatically by a script on the page. If you want to get just the styles inherited from the CSS file, then things get a bit trickier.