Paul Dixon Paul Dixon - 4 months ago 17
Javascript Question

How can I give keyboard focus to a DIV and attach keyboard event handlers to it?

I am building an application where I want to be able to click a rectangle represented by a DIV, and then use the keyboard to move that DIV by listing for keyboard events.

Rather than using an event listener for those keyboard events at the document level, can I listen for keyboard events at the DIV level, perhaps by giving it keyboard focus?

Here's a simplified sample to illustrate the problem:

<html>
<head>
</head>
<body>

<div id="outer" style="background-color:#eeeeee;padding:10px">
outer

<div id="inner" style="background-color:#bbbbbb;width:50%;margin:10px;padding:10px;">
want to be able to focus this element and pick up keypresses
</div>
</div>

<script language="Javascript">

function onClick()
{
document.getElementById('inner').innerHTML="clicked";
document.getElementById('inner').focus();

}

//this handler is never called
function onKeypressDiv()
{
document.getElementById('inner').innerHTML="keypress on div";
}

function onKeypressDoc()
{
document.getElementById('inner').innerHTML="keypress on doc";
}

//install event handlers
document.getElementById('inner').addEventListener("click", onClick, false);
document.getElementById('inner').addEventListener("keypress", onKeypressDiv, false);
document.addEventListener("keypress", onKeypressDoc, false);

</script>

</body>
</html>


On clicking the inner DIV I try to give it focus, but subsequent keyboard events are always picked up at the document level, not my DIV level event listener.

Do I simply need to implement an application-specific notion of keyboard focus?

I should add I only need this to work in Firefox.

Answer

Sorted - I added tabindex attribute to the target DIV, which causes it to pick up keyboard events, for example

<div id="inner" tabindex="0">
    this div can now have focus and recieve keyboard events
</div>

Information gleaned from http://www.w3.org/WAI/GL/WCAG20/WD-WCAG20-TECHS/SCR29.html

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