function draw() {
    var draw = false,
        context = document.getElementById('desc'),
        canvas = context.getContext('2d');

    canvas.lineWidth = 5;
    canvas.lineCap = 'round';

    context.addEventListener('mousedown', function() {
        draw = true;
        canvas.beginPath();
    }, false);

    context.addEventListener('mouseup', function() {
        draw = false;
    }, false);

    context.addEventListener('mousemove', function(e) {
        var newX = e.pageX - context.offsetLeft,
            newY = e.pageY - context.offsetTop;

        if (draw) {
            setTimeout(function() {
                canvas.lineTo(newX, newY);
                canvas.moveTo(newX, newY);
                canvas.stroke();
            }, 1);
        }
    });
}