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How to Determine if an Input Element is Focused in jQuery?

Barbara StreisandOriginal: 2024-11-21 09:47:141022browse

How to Use jQuery to Determine if an Input is Focused

In a website's front page, multiple

elements use the CSS :hover pseudo-class to display a border when the mouse hovers over them. One of these

elements contains a

that, with jQuery's help, maintains the border when any of its input elements have focus.

This setup works flawlessly, except in IE6, which does not support :hover on elements other than tags. To address this issue, jQuery is utilized to mimic CSS :hover using the $(#element).hover() method.

However, a problem arises when jQuery handles both the form's focus() and hover(). When an input element gains focus and the user moves the mouse in and out, the border disappears.

To resolve this behavior, consider using a conditional statement. For example, by checking if any inputs have focus on mouse out events, it is possible to prevent the border from fading away. Since jQuery lacks a :focus selector, alternative approaches need to be explored.

jQuery 1.6

jQuery 1.6 introduced a :focus selector, eliminating the need for custom implementations. Simply use:

$("..").is(":focus")

jQuery 1.5 and Below

Newer methods have emerged for testing focus, including Ben Alman's implementation:

jQuery.expr[':'].focus = function( elem ) {
  return elem === document.activeElement &amp;&amp; ( elem.type || elem.href );
};

This defines a custom selector, allowing usage like:

if ($("...").is(":focus")) {
  ...
}

Any jQuery Version

For retrieving the currently focused element:

$(document.activeElement)

To ensure compatibility with both jQuery versions 1.6 and lower:

(function ( $ ) {
    var filters = $.expr[":"];
    if ( !filters.focus ) { 
        filters.focus = function( elem ) {
           return elem === document.activeElement &amp;&amp; ( elem.type || elem.href );
        };
    }
})( jQuery );

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