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 th

Answer 1

No, the getComputedStyle() method on which jQuery's css() function depends cannot distinguish between an width computed from auto vs explicit widths. You can't tell if there was something set in the stylesheet, only from direct inline style="width: ..." (which is reflected in the element's .style.width property).

currentStyle works differently and will give you auto, however this is a non-standard IE extension.

If you really wanted to work it out, you could iterate over document.styleSheets, reading each of their declarations, getting the selector out and querying it to see whether your target element matched, then seeing if it contains a width rule. This would, however, be slow and not at all fun, especially as IE's styleSheet DOM differs from the other browsers. (And it still wouldn't cope with pseudo-elements and pseudo-classes, like :hover.)