function join_recipients(fields, form_id, target_field) {

    // get form
    var myForm = document.getElementById(form_id);
    // get values
    var recipient_urls = document.getElementsByName(fields);
    // get target field
    var target = document.getElementsByName(target_field);
    
    for(i = 0; i < recipient_urls.length; i++) {

        target[0].value +=", "+recipient_urls[i].value;
    }

}

function add_recipient(container_id) {

    // Get container
    var recipients_container = document.getElementById(container_id);
    recipients_container.innerHTML += "<label for=\"toEmail\">Weitere Empf&auml;nger-E-Mail-Adresse:<\/label>\n<input type=\"text\" name=\"toEmail\" \/>";
    
    //extra_recipients += 1;
}

function validateForm(form_id) {

// Get form
var myForm = document.getElementById(form_id);
var error = "";

// Element validation
//Input Boxen
    
error+= validate(myForm.fromName, "Bitte füllen Sie das Feld 'Mein Name' aus.");
error+= validate(myForm.fromEmail, "Bitte füllen Sie das Feld 'Meine E-Mail-Adresse' aus.");

    // Element E-Mailadresse
    if(!myForm.fromEmail.value == "" && !checkEmail(myForm.fromEmail.value)) {
        error+= "Sie haben keine gültige E-Mailadresse eingegeben.\n";
        highlightElement(myForm.fromEmail);
    } 
    
    //ein empfaenger
    if( !myForm.toEmail.length) {
      
        error+= validate(myForm.toEmail, "Bitte füllen Sie das Feld 'Empfänger-E-Mail-Adresse' aus.\n");
        
        if(!myForm.toEmail.value == "" && !checkEmail(myForm.toEmail.value)) {
            error+= "Sie haben keine gültige E-Mailadresse eingegeben.\n";
            highlightElement(myForm.toEmail);
        }
    
    //viele empfaenger
    } else {

        //for (var z=0; z < myForm.toEmail.length; z++) {

            error+= validate(myForm.toEmail[0], "Bitte füllen Sie das Feld 'Weitere Empfänger-E-Mail-Adresse' aus.");
            
            if(!myForm.toEmail[0].value == "" && !checkEmail(myForm.toEmail[0].value)) {
                error+= "Sie haben keine gültige E-Mailadresse eingegeben.\n";
                highlightElement(myForm.toEmail[0]);
            }
        //}
    }
	
	// Error handling
	if (error != "") {
		alert(error);
		return false;
	}
	
	return true;
}

// Highlights a required field
function highlightElement(el) {
	el.style.backgroundColor = "#FF2474";
	el.style.border = "1px solid red";
}

// Validates the given input field
function validate(el, msg) {
	if (el.value == "") {
		highlightElement(el)
		return msg + "\n";
	} else
		return "";
		
}
		
// Validates the given email address
function checkEmail(s) {
	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);
}