Form validation

window.onload = function () {
//Regular expressions
var reg_numbers = /^[0-9]+$/;
var reg_letters = /^[A-ZÆØÅa-zæøå]$/;
var reg_email = /^[a-zæøåA-ZÆØÅ0-9._-]+@[a-zæøåA-ZÆØÅ0-9.-]+\.[a-zæøåA-ZÆØÅ]{2,6}$/;

//Fields
var firstname = document.getElementById('mce-FNAME');
var email = document.getElementById('mce-EMAIL');
var form1 = document.getElementById('mc-embedded-subscribe-form');
var errormessage = document.getElementById('errormessage');


//Eventhandlers
firstname.onfocus = function (){
	firstname.value = "";
	firstname.style.color = "black";
};

email.onfocus = function (){
    email.value = "";
    email.style.color = "black";
};

form1.onsubmit = function(){
    error="";
    var result1 = isTooShort(firstname, "Indtast navn", 2);
    var result2 = checkPattern(email, reg_email, "Indtast gyldig email", 6);
    var result3 = checkPattern(firstname, reg_letters, "Indtast gyldigt navn", 2);

    errormessage.innerHTML = error;
    errormessage.style.color = "red";
    if(result1 && result2 && result3){
		return true;
	} else {
		return false;
	}
};

//Functions
    isTooShort = function (element, msg, minlength){
    var text = element.value;
    if (text.length < minlength) {
        error = error + msg + "<br>";
        element.style.color = "red";
        return false;
    }
    return true;
   };

    checkPattern = function (element, pattern, msg, minlenght) {
        if (!element.value.match(pattern)) {
            error = error + msg + "<br>";
            element.style.color = "red";
            return false;
        }
        return true;
    };
};