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// DX_email (STRING s [, BOOLEAN emptyOK == true])
// 
// 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
// null by default is ok, pass false in emptyOk if null not ok

function DX_email (s)
{   if ((s == null) || (s.length == 0)) 
       if (DX_email.arguments.length == 1) return true;
       else return (DX_email.arguments[1] == true);   
// is s whitespace?
    if (isWhitespace(s)) 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; //e-mail is good format
}

function isWhitespace (s) {   
var i;
var whitespace = " \t\n\r";

// 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;
}

// -->