function searchZip()
{
	var zip=document.getElementById("zip").value

	if(zip && zip.length==5)
	{
		if (IsNumeric(zip))
			document.forms[0].submit();
		else
			alert("Please enter 5 digit numeric value for Zip Code ");
	}		
	else
	{
		alert("Please enter 5 digit Zip Code ");
	}
}

function IsNumeric(sText)
{
   var ValidChars = "0123456789";
   var IsNumber=true;
   var Char;
 
   for (i = 0; i < sText.length && IsNumber == true; i++) 
   { 
      Char = sText.charAt(i); 
      if (ValidChars.indexOf(Char) == -1) 
      {
         IsNumber = false;
		 return;
      }
   }      
   return IsNumber;   
}