问题
Go into textfield and input a character. The debugger show you:
$( document.activeElement ) => work, node found + attribute you can read
$(":focus").css("background-color","red") => work
$( ':focus' ) => not work, no node found
Why? Any solutions?
In API doc it's say $( document.activeElement ) is the $( ':focus' ). Only a performance difference.
see: http://api.jquery.com/focus-selector/
Thanks!
<html>
<head>
<title>focus</title>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js" type="text/javascript"></script>
<script type="text/javascript">
$(function() {
$(document).keypress(function(event) {
$(":focus").css("background-color","red"); // <-- work
var f3 = $( ':focus' ); // <-- NOT work
var attr3 = f3.attr('tabindex');
var id3 = f3.attr('id');
f3.val(id3);
var f1 = $( document.activeElement ); // <-- work
var attr1 = f1.attr('tabindex');
var id1 = f1.attr('id');
console.log(id1);
return;
});
});
</script>
</head>
<body>
<h1>test focus</h1>
<label>TextBox : </label>
<form>
<input id="textbox1" type="text" size="50" tabindex="1"/><br>
<input id="textbox2" type="text" size="50" tabindex="2"/>
</form>
</body>
</html>
来源：https://stackoverflow.com/questions/16956906/focus-selector-not-work