// singleton Z object for generic purpose functionality
var Z =
{
  changePageStyle: function(cssName)
  {
    var className = cssName.replace(/\..*/g,"");
    var page = document.getElementById("page");
    page.className = "page " + className;
  },
  validateForm: function(el)
  {
    for (var i=0; i<el.elements.length; i++)
    {
      var field = el.elements[i];
      if (field.className.indexOf("email")!=-1)
      {
        if (!field.value.match(/^([a-zA-Z0-9_\.\-])+\@(([a-zA-Z0-9\-])+\.)+([a-zA-Z0-9]{2,4})+$/))
        {
          alert("Het veld " + field.name + " bevat geen geldig e-mail adres.");
          field.focus();
          return false;
        }
      }
      if (field.className.indexOf("required")!=-1)
      {
        if (field.value == "")
        {
          alert("Het veld " + field.name + " mag niet leeg zijn.");
          field.focus();
          return false;
        }
      }
    }
    return true;
  }
}