function validateForm(formname, fields, fieldnames)
{
	var tmpfield;	
	//check for required fields
	if(fields != "")           //if fieldnames not blank
	{
		var arrayFields = fields.split(",");
		var arrayFieldNames = fieldnames.split(",");
		for(i = 0; i < (arrayFields.length); i++)
		{
			tmpfield = arrayFields[i];

			if(tmpfield && document.forms[formname][tmpfield].value == "")
			{
				alert("Please fill in " + arrayFieldNames[i]);
				document.forms[formname][tmpfield].focus();
				return false;
			}
			if(tmpfield == "attachment") {
				var fileName = document.forms[formname][tmpfield].value;
				var index = fileName.lastIndexOf(".");
				var ext = fileName.substring(index, fileName.length);
				if (ext == ".txt" || ext == ".doc" || ext == ".pdf") {
					break;	
				} else {
					alert("File with extension .txt, .doc and .pdf are only allowed");	
					document.forms[formname][tmpfield].focus();
					return false;
				}
			}
		}
	}
}