Shift focus with arrow keys in JavaScript

Question

I want to be able to navigate through all the focusable elements on my webpage with the arrow key. So when the down-key is pressed the focus should shift to the focusable element beneath the current focussed element. You get the idea for the other arrow keys, when there is not a focusable element to shift to, the focus should remain the same.

This is what I got so far:

$(document).keydown(function(e){    

if (e.keyCode == 37) { //left

   var offset = $("*:focus").offset();

   var allElements = $("#container").find('a[href], area[href], input:not([disabled]), select:not([disabled]), textarea:not([disabled]), button:not([disabled]), iframe, object, embed, *[tabindex], *[contenteditable]');

   var arr = jQuery.makeArray(allElements);

   var topLeft = offset.left
   var minus = topLeft;
   var currentElement = $("*:focus");

   for(var i = 0; i < arr.length; i++)
   {

      if ( (arr[i].offset().left < offset.left)  // This doesn't work for some reason
        && ((offset.left - arr[i].offset().left) < minus))
      {
        currentElement = arr[i];
        minus = offset.left - arr[i].offset().left;
        topLeft = arr[i].offset().left;
      }


      currentElement.focus();
   }


   alert( "left pressed" );
   return false;
}

// Other Keys

});

the idea was to get all the focus-able elements and than pick select the one that is suited for the arrow and shift focus.

I'm not able to get this code to work (it contains a error) and I'm not completly sure it will even work.

Thnx in advance

[EDIT]: I guess I was a little vague. I do not only want to go left and right, but also up and down.

Answer 1

What I would do is much simpler. Just add a common class among the objects who should have this functionality (f.ex. "move") and use:

$(document).keydown(
    function(e)
    {    
        if (e.keyCode == 39) {      
            $(".move:focus").next().focus();

        }
        if (e.keyCode == 37) {      
            $(".move:focus").prev().focus();

        }
    }
);
​

See example: http://jsfiddle.net/uJ4PJ/

This code is much simpler and hopefully has all the functionality you need.

Just make sure the controls are in the correct order or this won't work properly.

Answer 2

After much trial and error, I developed this code that works :

function navigate(origin, sens) {
    var inputs = $('#form').find('input:enabled');
    var index = inputs.index(origin);
    index += sens;
    if (index < 0) {
        index = inputs.length - 1;
    }
    if (index > inputs.length - 1) {
        index = 0;
    }
    inputs.eq(index).focus();
}

$('input').keydown(function(e) {
    if (e.keyCode==37) {
        navigate(e.target, -1);
    }
    if (e.keyCode==39) {
        navigate(e.target, 1);
    }
});

right arrow acts as tab

left arrow acts as shift tab

Answer 3

Preview - http://jsfiddle.net/FehKh/ ;)

html:

<a href='jqwja' class="focusable">jajaj</a>
<a href='jjaasd' class="focusable focused">jajasdaaj</a>
<a href='jjqwea' class="focusable">jajaacasj</a>
<input value='iddqd' name="DoomII" class="focusable" />​

js:

// init
$('.focused').focus();

// actual code
$(document).keydown(function(e){    
    if (e.keyCode == 37) { // left
        if($('.focused').prev('.focusable').length)
            $('.focused').removeClass('focused').prev('.focusable').focus().addClass('focused');
    }
    if (e.keyCode == 39) { // right
        if($('.focused').next('.focusable').length)
            $('.focused').removeClass('focused').next('.focusable').focus().addClass('focused');
    }
});​