function emailCheck(){
	s = document.getElementById('fruehling').value;
	var a = false;
	var res = false;
	if(typeof(RegExp) == 'function'){
		var b = new RegExp('abc');
		if(b.test('abc') == true){a = true;}
	}

	if(a == true){
  		reg = new RegExp('^([a-zA-Z0-9\\-\\.\\_]+)'+
                   '(\\@)([a-zA-Z0-9\\-\\.]+)'+
                   '(\\.)([a-zA-Z]{2,4})$');
  		res = (reg.test(s));
 	}else{
		res = (s.search('@') >= 1 &&
         s.lastIndexOf('.') > s.search('@') &&
         s.lastIndexOf('.') >= s.length-5)
	}
	//
	return res;
}

function control(){
	res = emailCheck();
	if( res == false ){
		alert("Bitte überprüfe die E-Mail-Adresse!");
		return false;
	}
}