var ns6=document.getElementById&&!document.all

function RestrictInput(maxlength, e, placeholder)
{
 if (window.event&&event.srcElement.value.length>=maxlength)
  return false
 else
  if (e.target&&e.target==eval(placeholder)&&e.target.value.length>=maxlength)
   {
    var pressedkey=/[a-zA-Z0-9\.\,\/]/
    if (pressedkey.test(String.fromCharCode(e.which)))
     e.stopPropagation()
   }
}

function CountLimit(maxlength, e, placeholder)
{
 var lengthleft=maxlength-event.srcElement.value.length;
 var placeholderobj=document.all?document.all[placeholder]:document.getElementById(placeholder);
 if (window.event||e.target&&e.target==eval(placeholder))
  {
   if (lengthleft<0)
    event.srcElement.value=event.srcElement.value.substring(0, maxlength)
   placeholderobj.innerHTML=lengthleft
  }
}

function FieldLimit(form, limit, show)
{
 var limit_text = '';
 if (show) limit_text='Еще <b><span id="'+form.toString()+'">'+limit+'</span></b> символ(a, ов) можно ввести';
 if (document.all||ns6) document.write(limit_text)
 if (document.all)
  {
   eval(form).onkeypress=function() { return RestrictInput(limit, event, form) }
   eval(form).onkeyup=function() { CountLimit(limit, event, form) }
  }
 else if (ns6)
  {
   document.body.addEventListener('keypress', function(event) { RestrictInput(limit,event,form) }, true);
   document.body.addEventListener('keyup', function(event) { CountLimit(limit,event,form) }, true);
  }
}

function isEmailAddress(email)
{
 if (email.match(/^([a-zA-Z0-9])+([.a-zA-Z0-9_-])*@([a-zA-Z0-9_-])+(.[a-zA-Z0-9_-]+)+/))
  {
   return true;
  }
 else
  {
   return false;
  }
}

function isAlphaNumeric(value)
{
 if (value.match(/^[a-zA-Z0-9_]+$/))
  {
   return true;
  }
 else
  {
   return false;
  }
}

function isNumeric(value)
{
 if (value.match(/^[0-9]+$/))
  {
   return true;
  }
 else
  {
   return false;
  }
}