/**
 * Sets a Cookie with the given name and value.
 *
 * name       Name of the cookie
 * value      Value of the cookie
 * [expires]  Expiration date of the cookie (default: end of current session)
 * [path]     Path where the cookie is valid (default: path of calling document)
 * [domain]   Domain where the cookie is valid
 *              (default: domain of calling document)
 * [secure]   Boolean value indicating if the cookie transmission requires a
 *              secure transmission
 */
 
function toggle_balk() {
	var balk = getCookie('balk');
	if(balk) {
		deleteCookie("balk", "/", document.domain);		
	} else {
		setCookie("balk", 1, 36000, "/", document.domain, false);
	}
	heightEffect1.toggle();
}

function setCookie(name, value, expires, path, domain, secure) {
		var expires = new Date(50 * 365 * 1000 * 60 * 60 * 24); // 
    document.cookie= name + "=" + escape(value) +
        ((expires) ? "; expires=" + expires.toGMTString() : "") +
        ((path) ? "; path=" + path : "") +
        ((domain) ? "; domain=" + domain : "") +
        ((secure) ? "; secure" : "");
}

/**
 * Gets the value of the specified cookie.
 *
 * name  Name of the desired cookie.
 *
 * Returns a string containing value of specified cookie,
 *   or null if cookie does not exist.
 */
function getCookie(name) {
    var dc = document.cookie;
    var prefix = name + "=";
    var begin = dc.indexOf("; " + prefix);
    if (begin == -1) {
        begin = dc.indexOf(prefix);
        if (begin != 0) return null;
    } else {
        begin += 2;
    }
    var end = document.cookie.indexOf(";", begin);
    if (end == -1) {
        end = dc.length;
    }
    return unescape(dc.substring(begin + prefix.length, end));
}

/**
 * Deletes the specified cookie.
 *
 * name      name of the cookie
 * [path]    path of the cookie (must be same as path used to create cookie)
 * [domain]  domain of the cookie (must be same as domain used to create cookie)
 */
function deleteCookie(name, path, domain) {
    if (getCookie(name)) {
        document.cookie = name + "=" +
            ((path) ? "; path=" + path : "") +
            ((domain) ? "; domain=" + domain : "") +
            "; expires=Thu, 01-Jan-70 00:00:01 GMT";
    }
}

function check() {
 	var fieldsOK;
	if (document.data.naam.value=="") {
	 alert ("Voor de verzending is het noodzakelijk dat u uw naam invult");
	 document.data.naam.focus();
	 fieldsOK=false;
	}
	if ((document.data.telefoon.value=="") && (fieldsOK!=false)) {
	 alert ("Voor de verzending is het noodzakelijk dat u uw telefoonnummer invult");
	 document.data.telefoon.focus();
	 fieldsOK=false;
	}
	if ((document.data.email.value=="") && (fieldsOK!=false)) {
	 alert ("Voor de verzending is het noodzakelijk dat u uw e-mail adres invult");
	 document.data.email.focus();
	 fieldsOK=false;
	}
	if((document.data.email.value.indexOf("@") < 1) && (fieldsOK!=false)) {
	 alert("Voor de verzending is het noodzakelijk dat u een correct e-mail adres invult");
	 document.data.email.focus();
	 fieldsOK=false;
	}
	if((document.data.email.value.indexOf(".") < 0) && (fieldsOK!=false))	{
	 alert("Voor de verzending is het noodzakelijk dat u een correct e-mail adres invult");
	 document.data.email.focus();
	 fieldsOK=false;
	}

	if (fieldsOK==false) {
	 	return false;
	} else {
    return true;
  }
}