<script >
function display(x)
{
  win = window.open();
  for (var i in x) win.document.write(i+" = "+x[i]+"
");
}

// ***** data arrays ***********************************************************

// ***** options *****

var form_validation_options =
  {
    "override_enter"    : true,
    "override_bksp"     : true
  };

// ***** messages *****

var form_validation_alerts =
  {
    ">"      : "%%name%% should be more than %%num%%!",
    "<"      : "%%name%% should be less than %%num%%!",
    ">="     : "%%name%% should be more or equal to %%num%%!",
    "<="     : "%%name%% should be less or equal to %%num%%!",
    "ch"     : "%%name%% contains invalid characters!",
    "chnum_" : "%%name%% contains invalid characters!",
    "cnt >"  : "you should select more than %%num%% %%name%%!",
    "cnt <"  : "you should select less than %%num%% %%name%%!",
    "cnt >=" : "you should select at least %%num%% %%name%%!",
    "cnt <=" : "you should select at most %%num%% %%name%%!",
    "cnt ==" : "you should select %%num%% %%name%%!",
    "date"   : "please, enter a valid %%name%%!",
    "email"  : "please, enter a valid e-mail address!",
    "empty"  : "please, enter %%name%%!",
    "len >"  : "%%name%% should contain more than %%num%% characters!",
    "len <"  : "%%name%% should contain less than %%num%% characters!",
    "len >=" : "%%name%% should contain at least %%num%% characters!",
    "len <=" : "%%name%% should contain at most %%num%% characters!",
    "len ==" : "%%name%% should contain %%num%% characters!",
    "num"    : "%%name%% is not a valid number!",
    "radio"  : "please, select %%name%%!",
    "select" : "please, select %%name%%!",
    "terms"  : "you must agree to the terms first!"
  };

// ***** form field types *****

var form_validation_nonedit = " button hidden reset submit ";
var form_validation_edit    = " checkbox file password radio select-multiple select-one text textarea ";
var form_validation_type    = " file password text textarea ";
var form_validation_check   = " checkbox radiox select-multiple select-one ";

// ***** alert *****************************************************************

function form_validation_alert(type, name, num)
{
  name = name.replace(/^w*(w*)w*$/, "$1");

  msg = form_validation_alerts[type];
  msg = msg.replace("%%name%%", name.substr(0, 1).touppercase()+name.substr(1, name.length-1).tolowercase());
  msg = msg.replace("%%name%%", name.tolowercase());
  msg = msg.replace("%%num%%", num);

  alert(msg);

  return false;
}

// ***** behave ****************************************************************

function form_validation_behave(control, key, rules)
{
  rules = form_validation_rules2array(rules);

  for (var i = 0; i < rules.length; i++)
  {
    var rule = rules[i].split(/s*:s*/);

    if (rule.length < 2) continue;
    if (!form_validation_instring(" "+rule[0]+" ", control.name)) continue;

    rule[1] = rule[1].split(/s+/);

    switch (rule[1][0])
    {
      // ***** count *****

      case "count":
        document.getelementbyid(rule[1][1]).innerhtml = control.value.length;
        if (rule[1].length >= 5)
          if (control.value.length < rule[1][2])
               document.getelementbyid(rule[1][1]).style.color = rule[1][3];
          else document.getelementbyid(rule[1][1]).style.color = rule[1][4];
        break;

      // ***** next *****

      case "next":
        if (control.value.length == rule[1][1]) form_validation_focusnext(control);
        break;

      // ***** prev *****

      case "prev":
        if (control.value.length == 0 && key == 8) form_validation_focusprev(control);
        break;
    }
  }

  return true;
}

// ***** getelement ************************************************************

function form_validation_getelement(tag, name)
{
  for (var i = 0; i < tag.elements.length; i++)
    if (tag.elements[i].name == name) return tag.elements[i];
  return undefined;
}

// ***** instring **************************************************************

function form_validation_instring(str, val)
{
  return str.indexof(" "+val+" ") >= 0;
}

// ***** focusnext *************************************************************

function form_validation_focusnext(tag)
{
  for (var i = 0; i < tag.form.elements.length; i++)
    if (tag.form.elements[i] == tag)
      for (var j = i+1; j < tag.form.elements.length; j++)
        if (form_validation_instring(form_validation_edit, tag.form.elements[j].type))
        {
          if (form_validation_instring(form_validation_type, tag.form.elements[j].type))
               form_validation_setselection(tag.form.elements[j], 0, 0, "frend");
          else tag.form.elements[j].focus();
          return false;
        }

  return true;
}

// ***** focusprev *************************************************************

function form_validation_focusprev(tag)
{
  for (var i = 0; i < tag.form.elements.length; i++)
    if (tag.form.elements[i] == tag)
      for (var j = i-1; j >= 0; j--)
        if (form_validation_instring(form_validation_edit, tag.form.elements[j].type))
        {
          if (form_validation_instring(form_validation_type, tag.form.elements[j].type))
               form_validation_setselection(tag.form.elements[j], 0, 0, "frend");
          else tag.form.elements[j].focus();
          return false;
        }

  return true;
}

// ***** initialize ************************************************************

function form_validation_initialize(control, rules)
{
  rules = form_validation_rules2array(rules);

  for (var i = 0; i < rules.length; i++)
  {
    var rule = rules[i].split(/s*:s*/);

    if (rule.length < 2) continue;
    if (!form_validation_instring(" "+rule[0]+" ", control.name)) continue;

    rule[1] = rule[1].split(/s+/);

    switch (rule[1][0])
    {
      // ***** count *****

      case "count":
        document.getelementbyid(rule[1][1]).innerhtml = control.value.length;
        if (rule[1].length >= 5)
          if (control.value.length < rule[1][2])
               document.getelementbyid(rule[1][1]).style.color = rule[1][3];
          else document.getelementbyid(rule[1][1]).style.color = rule[1][4];
        break;
    }
  }

  return true;
}

// ***** onchange **************************************************************

function form_validation_onchange(e)
{
  var ie  = navigator.appname == "microsoft internet explorer";
  var tag = ie ? window.event.srcelement : e.target;

  return true;
}

// ***** onkeypress ************************************************************

function form_validation_onkeypress(e)
{
  var ie  = navigator.appname == "microsoft internet explorer";
  var tag = ie ? window.event.srcelement : e.target;
  var key = ie ? window.event.keycode    : e.which;

  if (form_validation_options["override_backspace"])
    if (key == 8)
      return form_validation_instring(form_validation_type, tag.type);

  if (form_validation_options["override_enter"])
    if (key == 13 && tag.type != "textarea")
      return form_validation_focusnext(tag);

  return true;
}

// ***** onkeyup ***************************************************************

function form_validation_onkeyup(e)
{
  var ie  = navigator.appname == "microsoft internet explorer";
  var tag = ie ? window.event.srcelement : e.target;
  var key = ie ? window.event.keycode    : e.which;

  var behaviours = form_validation_getelement(tag.form, "form_validation_behaviours");

  if (behaviours !== undefined) form_validation_behave(tag, key, behaviours.value);
}

// ***** onsubmit **************************************************************

function form_validation_onsubmit(e)
{
  var ie  = navigator.appname == "microsoft internet explorer";
  var tag = ie ? window.event.srcelement : e.target;
  if (tag.tagname != "form") tag = tag.form;

  // ***** validate fields *****

  var rules = form_validation_getelement(tag, "form_validation_rules");

  if (rules !== undefined)
    for (var i = 0; i < tag.elements.length; i++)
      if (!form_validation_validate(tag.elements[i], rules.value))
      {
        tag.elements[i].focus();
        if (tag.elements[i].select !== undefined) tag.elements[i].select();
        return false;
      }

  // ***** unset fields *****

  for (var i = 0; i < tag.elements.length; i++)
  {
    if (tag.elements[i].name == "form_validation_rules")      tag.elements[i].value = "";
    if (tag.elements[i].name == "form_validation_behaviours") tag.elements[i].value = "";
  }

  return true;
}

// ***** register **************************************************************

function form_validation_register()
{
  for (var i = 0; i < document.forms.length; i++)
    with (document.forms[i])
    {
      var rules      = form_validation_getelement(document.forms[i], "form_validation_rules");
      var behaviours = form_validation_getelement(document.forms[i], "form_validation_behaviours");

      if (rules === undefined && behaviours === undefined) continue;

      onsubmit = form_validation_onsubmit;

      for (var j = 0; j < elements.length; j++)
      {
        if (behaviours !== undefined) form_validation_initialize(elements[j], behaviours.value);

        elements[j].onchange   = form_validation_onchange;
        elements[j].onkeypress = form_validation_onkeypress;
        elements[j].onkeyup    = form_validation_onkeyup;
      }
    }
}

// ***** rules2array ***********************************************************

function form_validation_rules2array(rules)
{
  rules = rules.replace(/^(s*)(s.*)/, "$2");
  rules = rules.replace(/(.*s)(s*)$/, "$1");
  return rules.split(/s*;s*/);
}

// ***** setselection **********************************************************

function form_validation_setselection(control, start, end, mode)
{
  if (control.focus) control.focus();

  // ***** netscape *****

  if (control.selectionstart !== undefined &&
      control.selectionend   !== undefined)
  {
    offset = control.selectionstart;
    if (mode == "frstart") offset = 0;
    if (mode ==   "frend") offset = control.textlength;

    control.selectionstart = offset+start;
    control.selectionend   = offset+end;

    return true;
  }

  // ***** ie *****

  if (control.select                 !== undefined &&
      document.selection             !== undefined &&
      document.selection.createrange !== undefined)
  {
    if (mode == "frstart" || mode == "frend") control.select();

    range = document.selection.createrange();

    if (mode == "frstart") range.moveend  ("character", -range.text.length);
    if (mode == "frend")   range.movestart("character",  range.text.length);

    range.movestart("character", start);
    range.moveend  ("character", end);
    range.select();

    return true;
  }

  return false;
}

// ***** validate **************************************************************

function form_validation_validate(control, rules)
{
  rules = form_validation_rules2array(rules);

  for (var i = 0; i < rules.length; i++)
  {
    var rule = rules[i].split(/s*:s*/);

    if (rule.length < 2) continue;
    if (!form_validation_instring(" "+rule[0]+" ", control.name)) continue;

    rule[1] = rule[1].split(/s+/);

    switch (rule[1][0])
    {
      // ***** comparison *****

      case ">":
        if (control.value == "" || isnan(control.value))
          return form_validation_alert("num", control.name, 0);
        if (control.value <= rule[1][1])
          return form_validation_alert(">", control.name, rule[1][1]);
        break;

      case "<":
        if (control.value == "" || isnan(control.value))
          return form_validation_alert("num", control.name, 0);
        if (control.value >= rule[1][1])
          return form_validation_alert("<", control.name, rule[1][1]);
        break;

      case ">=":
        if (control.value == "" || isnan(control.value))
          return form_validation_alert("num", control.name, 0);
        if (control.value < rule[1][1])
          return form_validation_alert(">=", control.name, rule[1][1]);
        break;

      case "<=":
        if (control.value == "" || isnan(control.value))
          return form_validation_alert("num", control.name, 0);
        if (control.value > rule[1][1])
          return form_validation_alert("<=", control.name, rule[1][1]);
        break;

      // ***** ch *****

      case "ch":
        if (!/^([a-za-z]+)$/.test(control.value))
          return form_validation_alert("ch", control.name, 0);
        break;

      // ***** chnum_ *****

      case "chnum_":
        if (!/^(w+)$/.test(control.value))
          return form_validation_alert("chnum_", control.name, 0);
        break;

      // ***** cnt *****

      case "cnt":
        var cnt = 0;

        if (control.type == "select-multiple")
          for (var k = 0; k < control.options.length; k++)
            if (control.options[k].selected) cnt++;

        if (control.type == "checkbox")
          with (control.form)
            for (var k = 0; k < elements.length; k++)
              if (elements[k].name == control.name && elements[k].checked) cnt++;

        if (rule[1][1] == ">" && cnt <= rule[1][2])
          return form_validation_alert("cnt >", control.name, rule[1][2]);
        if (rule[1][1] == "<" && cnt >= rule[1][2])
          return form_validation_alert("cnt <", control.name, rule[1][2]);
        if (rule[1][1] == ">=" && cnt < rule[1][2])
          return form_validation_alert("cnt >=", control.name, rule[1][2]);
        if (rule[1][1] == "<=" && cnt > rule[1][2])
          return form_validation_alert("cnt >=", control.name, rule[1][2]);
        if (rule[1][1] == "==" && cnt != rule[1][2])
          return form_validation_alert("cnt ==", control.name, rule[1][2]);

        break;

      // ***** date *****

      case "date":
        rule[0] = rule[0].split(/s+/);

        if (rule[0].length == 3)
        {
          var year;
          var month;
          var day;

          with (control.form)
            for (var k = 0; k < elements.length; k++)
            {
              if (elements[k].name == rule[0][0]) year  = elements[k];
              if (elements[k].name == rule[0][1]) month = elements[k];
              if (elements[k].name == rule[0][2]) day   = elements[k];
            }

          if (year !== undefined && month !== undefined && day !== undefined)
          {
            if (control == year)
              if (year.value  == "" || isnan(year.value))
                return form_validation_alert("date", year.name, 0);
            if (control == month)
              if (month.value == "" || isnan(month.value) || month.value < 0 || month.value > 12)
                return form_validation_alert("date", month.name, 0);
            if (control == day)
            {
              if (day.value   == "" || isnan(day.value)   || day.value   < 0 || day.value   > 31)
                return form_validation_alert("date", day.name, 0);
              date = new date(year.value, month.value, day.value);
              if (date.getdate() != day.value)
                return form_validation_alert("date", day.name, 0);
            }
          }
        }

        break;

      // ***** email *****

      case "email":
        if (!/^(w+.)*(w+)@(w+.)+(w+)$/.test(control.value))
          return form_validation_alert("email", control.name, 0);
        break;

      // ***** empty *****

      case "empty":
        if (form_validation_instring(form_validation_type, control.type) && control.value == "")
          return form_validation_alert("empty", control.name, 0);
        break;

      // ***** len *****

      case "len":
        if (rule[1][1] == ">" && control.value.length <= rule[1][2])
          return form_validation_alert("len >", control.name, rule[1][2]);
        if (rule[1][1] == "<" && control.value.length >= rule[1][2])
          return form_validation_alert("len <", control.name, rule[1][2]);
        if (rule[1][1] == ">=" && control.value.length < rule[1][2])
          return form_validation_alert("len >=", control.name, rule[1][2]);
        if (rule[1][1] == "<=" && control.value.length > rule[1][2])
          return form_validation_alert("len <=", control.name, rule[1][2]);
        if (rule[1][1] == "==" && control.value.length != rule[1][2])
          return form_validation_alert("len ==", control.name, rule[1][2]);
        break;

      // ***** num *****

      case "num":
        if (control.value == "" || isnan(control.value))
          return form_validation_alert("num", control.name, 0);
        break;

      // ***** radio *****

      case "radio":
        var checked = false;
        with (control.form)
          for (var k = 0; k < elements.length; k++)
            if (elements[k].name == control.name && elements[k].checked)
              checked = true;
        if (!checked) return form_validation_alert("radio", control.name, 0);

      // ***** select *****

      case "select":
        if (control.value == rule[1][1])
          return form_validation_alert("select", control.name, 0);
        break;

      // ***** terms *****

      case "terms":
        if (!control.checked)
          return form_validation_alert("terms", control.name, 0);
        break;
    }
  }

  return true;
}

// ***** initialize forms ******************************************************

form_validation_register();
</script>