// formcheck.js
//
// This is a set of JavaScript functions for validating input on an HTML form.
//

// isEmail (STRING s [, BOOLEAN emptyOK])
// 
// Email address must be of form a@b.c -- in other words:
// * there must be at least one character before the @
// * there must be at least one character before and after the .
// * the characters @ and . are both required
//
// For explanation of optional argument emptyOK,
// see comments of function isInteger.

function isEmail (s)
{   if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return false;
       else return (isEmail.arguments[1] == true);
   
    // is s whitespace?
    if (isWhitespace(s)) return false;
	if (s.indexOf(":",0) != -1) return false;
    
    // there must be >= 1 character before @, so we
    // start looking at character position 1 
    // (i.e. second character)
    var i = 1;
    var sLength = s.length;

    // look for @
    while ((i < sLength) && (s.charAt(i) != "@"))
    { i++
    }

    if ((i >= sLength) || (s.charAt(i) != "@")) return false;
    else i += 2;

    // look for .
    while ((i < sLength) && (s.charAt(i) != "."))
    { i++
    }

    // there must be at least one character after the .
    if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
    else return true;
}

// whitespace characters
var whitespace = " \t\n\r";

// Check whether string s is empty.

function isEmpty(s) {
  return ((s == null) || (s.length == 0))
}

// Returns true if string s is empty or 
// whitespace characters only.

function isWhitespace (s)

{   var i;

    // Is s empty?
    if (isEmpty(s)) return true;

    // Search through string's characters one by one
    // until we find a non-whitespace character.
    // When we do, return false; if we don't, return true.

    for (i = 0; i < s.length; i++)
    {   
        // Check that current character isn't whitespace.
        var c = s.charAt(i);

        if (whitespace.indexOf(c) == -1) return false;
    }

    // All characters are whitespace.
    return true;
}


var validChars = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";

function isAlphanumeric (s) {
  var tmp = s.toUpperCase();
  for (i = 0; i < tmp.length; i++) {   
    var c = tmp.charAt(i);
    if (validChars.indexOf(c) == -1) {
      return false;
    }
  }
  return true;
}

function isNumeric (s) {
  var i;
 
  for(i = 0; i < s.length; i++) {
  if(isNaN(parseInt(s.substring(i, i + 1)))) {
    return false;
  }
}
return true;
}