function WritetoDiv(name, message) {
    if (document.layers) {
        document.layers[name].document.close();
        document.layers[name].document.write(message);
        document.layers[name].document.close();
    } else {
        if (document.all) {
            eval("document.all." + name + ".innerHTML='" + message + "'");
        } else {
            document.getElementById(name).innerHTML = message;
        }
    }
}

function correctPNG() // correctly handle PNG transparency in Win IE 5.5 or higher.
{
	for(var i=0; i<document.images.length; i++)
	{
		var img = document.images[i];
		var imgName = img.src.toUpperCase();
		if (imgName.substring(imgName.length-3, imgName.length) == "PNG")
		{
			var imgID = (img.id) ? "id='" + img.id + "' " : "";
			var imgClass = (img.className) ? "class='" + img.className + "' " : "";
			var imgTitle = (img.title) ? "title='" + img.title + "' " : "title='" + img.alt + "' ";
			var imgStyle = "display:inline-block;" + img.style.cssText;
			if (img.align == "left") 
				imgStyle = "float:left;" + imgStyle;
			if (img.align == "right") 
				imgStyle = "float:right;" + imgStyle;
			if (img.parentElement.href) 
				imgStyle = "cursor:hand;" + imgStyle;
			var strNewHTML = "<span " + imgID + imgClass + imgTitle
			+ " style=\"" + "width:" + img.width + "px; height:" + img.height + "px;" + imgStyle + ";"
			+ "filter:progid:DXImageTransform.Microsoft.AlphaImageLoader"
			+ "(src=\'" + img.src + "\', sizingMethod='scale');\"></span>";
			img.outerHTML = strNewHTML;
			i = i-1;
		}
	}
}
window.attachEvent("onload", correctPNG);







function validate_form() {
  validity = true; 
  if (!check_empty(document.form.voorletters.value))
        { validity = false; alert('U heeft geen voorletters ingevuld!'); }

   if (!check_empty(document.form.naam.value))
        { validity = false; alert('U heeft geen naam ingevuld!'); }
 
  if (!check_email(document.form.email.value))
        { validity = false; alert('Het E-mail adres is ongeldig!'); }
return validity;
}



function check_empty(text) {
  return (text.length > 0); // returns false if empty
}



function check_email(adres) {
  if ((adres == "")
    || (adres.indexOf ('@') == -1)
    || (adres.indexOf ('.') == -1))
      return false;
  return true;
}