In Javascript find if a checkbox is focused

Question

In Javascript how can I tell if a checkbox has focus or not?

I thought there would be a method or property called isfocused. But apparently not.

By in focus I mean they've tabbed to it using the keyboard and at this point pressing space would check the box.

Why do you need to know if it 'has focus'? Does that mean they've selected the label next to it? Only 'chec' and uncheck seem to matter. — George Stocker, Feb 11 '09 at 00:43
In the javascript I'm responding to some keyboard events and I need to know if it's the last checkbox in the list. — Ray, Feb 11 '09 at 00:47
Then I don't need to worry about it. It comes down to if they tab past the last checkbox in the list, I need to hide the list. If they use the mouse, the list will be closed anyway. — Ray, Feb 11 '09 at 00:51

score 4 · Accepted Answer · answered Feb 11 '09 at 00:51

4

Create an event handler that is wired to the onfocus event. When it's called, set a global var to remember that it's got the focus. Write another one on the onblur event which clears the variable.

answered Feb 11 '09 at 00:51

Denis Hennessy

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[This answer is better](https://stackoverflow.com/questions/36430561/how-can-i-check-if-my-element-id-has-focus) – Илья Зеленько Mar 29 '19 at 09:59

score 1 · Answer 2 · answered Feb 11 '09 at 00:50

1

There is a onfocus event that fires when an element receives focus.

<script type="text/javascript">

var isFocused = false;

</script>

<input type="checkbox" name="team" value="team" onfocus="javascript:isFocused = true;">Spurs<br>

answered Feb 11 '09 at 00:50

regex

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score 1 · Answer 3 · answered Feb 11 '09 at 00:51

1

You might have to just hook into the onfocus and onblur events for the checkbox to keep track of when it gets and loses focus.

answered Feb 11 '09 at 00:51

Marc Novakowski

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score 1 · Answer 4 · answered Feb 11 '09 at 01:07

Here's an example of the basics of an implementation that might help you. Note: the output stuff is just for demonstration purposes and not part of the actual solution.

<html>
<head>
    <script type="text/javascript">

    onload = function()
    {
        var f = document.forms.test;
        f.focusedElem = null;
        updateOutput( f );

        for ( var i = 0, l = f.elements.length, elem; i < l; i++ )
        {
            elem = f.elements[i];
            elem.onfocus = function( elem )
            {
                return function()
                {
                    elem.form.focusedElem = elem;
                    updateOutput( elem.form );
                }
            }( elem )

            elem.onblur = function()
            {
                f.focusedElem = null;
                updateOutput( f )
            }
        }
    }

    function updateOutput( f )
    {
        document.getElementById( 'output' ).innerHTML = ( null == f.focusedElem ) ? 'Nothing!' : f.focusedElem.id;
    }

    </script>
</head>
<body>

<form name="test">

<input type="checkbox" name="foo" id="foo1">
<input type="checkbox" name="foo" id="foo2">
<input type="checkbox" name="foo" id="foo3">
<input type="checkbox" name="foo" id="foo4">

</form>

What has focus? <span id="output"></span>

</body>
</html>

In Javascript find if a checkbox is focused

4 Answers4

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