How to determine if a field has focus?

Very similar to How do I find out which DOM element has the focus? except that I'm not trying find the field that has focus, I just 开发者_运维问答need to know if a particular one already has focus. Is that possible?

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You can try

$("input#id").is(":focus")

Edit: You should read this post if you plan to use it on older browsers. http://forum.jquery.com/topic/is-the-focus-selector-valid

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You can do this rather simply with jQuery: $(el).is(":focus")