Question

I want to try this example, but it is doesn’t work. Why ?

<div id="test"></div>
<script>
    $('#test').focus();
    alert($("*:focus").attr("id"))
</script> 

Answer 1

Note, as others have mentioned, not all elements can be focussed by default. You must add the tabindex attribute to them to make those elements focussable:

<div id="test" tabindex="0"></div>
<script>
    $('#test').focus();
    alert($("*:focus").attr("id"))
</script> 

When the tabindex attribute is applied, your original code works. See this working example.

---

In plain JavaScript, document.activeElement should return the focussed element, if there is one. It can also return an element that is active, but not focussed. The best way to handle it is to check if the element is focussed:

function getFocussedElement() {
    var el;
    if ((el = document.activeElement) && el != document.body)
        return el;
    else
        return null;
}

It’s worth mentioning that this approach should be much faster than querying with selectors. Be aware that activeElement isn’t part of any standard, but it is supported by all major browsers.