Javascript - 如何使用键盘箭头键更改焦点在列表中的链接

Question

I'm able to change focus when the links are not wrapped in other elements.

This works:

HTML

<a id="first" href="#" class='move'>Link</a>
<a href="#" class='move'>Link</a>
<a href="#" class='move'>Link</a>

JS (with jQuery)

$(document).keydown(
    function(e)
    {    
        // Down key
        if (e.keyCode == 40) {      
            $(".move:focus").next().focus();       
        }

        // Up key
        if (e.keyCode == 38) {      
            $(".move:focus").prev().focus();       
        }
    }
);

Demo Fiddle

But how do I achieve the same thing when the links are inside a list for example? Like this

<ul>
    <li>
        <a id="first" href="#" class='move'>Link</a>
    </li>
    <li>
        <a href="#" class='move'>Link</a>
    </li>
    <li>
        <a href="#" class='move'>Link</a>
    </li>
</ul> 

Answer 1

You can use .closest() to find the parent element then use .next() to get the next li, then use .find() to get the next .move

    if (e.keyCode == 40) {      
        $(".move:focus").closest('li').next().find('a.move').focus();   
    }

    // Up key
    if (e.keyCode == 38) {      
        $(".move:focus").closest('li').prev().find('a.move').focus();   
    }

DEMO

Answer 2

if (e.keyCode == 40) {      
  $(".move:focus").parent().next().find('a').focus();   
}
if (e.keyCode == 38) {      
  $(".move:focus").parent().prev().find('a').focus();   
}

Answer 3

If you happen to want your focus to cycle when reaching the end of the list, you can do something like this:

var $li = $('li'),

$move = $(".move").click(function () {
    this.focus();
});

$(document).keydown(function(e) {
    if (e.keyCode == 40 || e.keyCode == 38) {
        var inc = e.keyCode == 40 ? 1 : -1,
            move = $move.filter(":focus").parent('li').index() + inc;
        $li.eq(move % $li.length).find('.move').focus();
    }
});

$move.filter(':first').focus();

Demo: http://jsfiddle.net/WWQPR/5/