// Rejects: empty strings or strings full of blanks, 
//          strings without @ or without . (dot) 
// Rejects: A@, @B, A@B, .A@B, A@B., A@.B 
// Accepts: A@B.C, A.B@C.D

function ValidEmail(s) { 
var Count; 
var s2; 
// empty or blank email 
if (EmptyString(s) == true) return (false); 
// email without @ 
if (s.indexOf('@') == -1) return (false); 
// email with @ as the 1st char 
if (s.indexOf('@') == 0) return (false); 
// email with @ as the last char 
if ((s.indexOf('@')+1) == s.length) return (false); 
// email without . 
if (s.indexOf('.') == -1) return (false); 
// email with . as the 1st char 
if (s.indexOf('.') == 0) return (false); 
// email with . as the last char 
if ((s.indexOf('.')+1) == s.length) return (false); 

// Now look for the first . after the first @ 
// s2 = string after the first @ 
s2=s.substring(s.indexOf('@')+1,s.length); 
// email without a dot after the first @ 
if (s2.indexOf('.') == -1) return (false); 
// email dot right after the first @ 
if (s2.indexOf('.') == 0) return (false); 
return (true); 
} 

function EmptyString(s) { 
var Count; 
var Nblank = 0; 
if (s.length == 0) return (true); // empty string 
// count the number of blank chars 
for (Count = 0; Count < s.length; Count++) { 
if (s.charAt(Count) == " ") Nblank++; 
} 
if (Nblank == s.length) 
return (true); 
else 
return (false); 
}