var InputNumber = Class.create();

InputNumber.inRange = function(n) 
{
    return n >= 48 && n <= 57;
};

Object.extend(InputNumber.prototype, 
{
    initialize: function(obj) 
	{
        this.obj = $(obj);
        this.obj.onkeypress = this.keytest.bindAsEventListener(this);
    },
    
    keytest: function(evt) 
	{
        var e = evt || event;
        var code = e.keyCode || e.which || e.charCode;
        
        switch(code) 
		{
            case Event.KEY_BACKSPACE:
            case Event.KEY_DELETE:
            case Event.KEY_LEFT:
            case Event.KEY_RIGHT:
            case Event.KEY_HOME:
            case Event.KEY_END:
            case Event.KEY_TAB:
            case Event.KEY_RETURN:
			break;
            default:
				if(InputNumber.inRange(code) == false)
				{
					Event.stop(e);
				}
        }
    }
});