Arrow keys Move Div

by oterox

HTML

<div id="pane">
    <div id="box"></div>
</div>

CSS

#pane {
    position:relative;
    width:300px; height:300px;
    border:2px solid red;
}
    
#box {
    position:absolute; top:140px; left:140px;
    width:20px; height:20px;          
    background-color:black;
}

JavaScript

var pane = $('#pane'),
    box = $('#box'),
    w = pane.width() - box.width(),
    d = {},
    x = 3;

function newv(v,a,b) {
    var n = parseInt(v, 10) - (d[a] ? x : 0) + (d[b] ? x : 0);
    return n < 0 ? 0 : n > w ? w : n;
}

$(window).keydown(function(e) { d[e.which] = true; });
$(window).keyup(function(e) { d[e.which] = false; });

setInterval(function() {
    box.css({
        left: function(i,v) { return newv(v, 37, 39); },
        top: function(i,v) { return newv(v, 38, 40); }
    });
}, 20);