jQuery/Javascript css("width") / check if style is defined in css?

Question

I have a stylesheet which defines default width for images. When I read the image width style with jQuery width() it returns the right width. It also returns the same width when I call css("width"). But if there is no width defined in the stylesheet the function css("width") will also return the computed width() value but won't say undefined or auto or something like that.

Any ideas how I could find out if style is or is not defined in the CSS code?

Solution works for me cross browser. Thanks to everyone for helping:

$(this).addClass("default_width_check");
var width = ($(this).width() == 12345) ? 'none-defined' : $(this).width();
var height = ($(this).height() == 12345) ? 'none-defined' : $(this).height();
$(this).removeClass("default_width_check");

.default_width_check {
    width: 12345;
}

Answer 1

I have a workaround idea that might work.

Define a class named default_width before all other style sheets:

.default_width { width: 1787px }  
/* An arbitrary value unlikely to be an image's width, but not too large
   in case the browser reserves memory for it */

to find out whether an image has a width set:

• Clone it in jQuery: element = $("#img").clone()

• give the cloned element the default_width class: element.addClass("default_width")

• If its width is 1787px, it has no width set - or, of course, is natively 1787px wide, which is the only case in which this method will not work.

I'm not entirely sure whether this will work, but it might. Edit: As @bobince points out in the comments, you will need to insert the element into the DOM for all classes to be applied correctly, in order to make a correct width calculation.