var bonusCodeDone = false;
jQuery(document).ready(function() {
    jQuery('.bonuscode').keyup(function(event) {
        var maxCount = 4;
        var next = false;
        switch(jQuery(this).attr('name')){
            case 'bonus1':
                maxCount = 3;
                next = 'bonus2';
                break;
            case 'bonus2':
                next = 'bonus3';
                break;
            case 'bonus3':
                next = 'bonus4';
                break; 
            case 'bonus4':
                bonusCodeDone = true;
                maxCount = 3;
                next = 'submit';
                break;
            default:
            	break;
        }                
        if( next && !bonusCodeDone) {
	        if( jQuery(this).attr('value').length >= maxCount) {
                    jQuery('input[name="'+next+'"]').focus();
	        }
        } else {
            if( jQuery(this).attr('value').length < maxCount) {
                bonusCodeDone = false;
            }
        }
    });
});