JavaScript does not offer Left and Right functions. Use the following functions to extract the left or the right part of a string.
function Left(str, n){ if (n <= 0) return ""; else if (n > String(str).length) return str; else return String(str).substring(0,n);}function Right(str, n){ if (n <= 0) return ""; else if (n > String(str).length) return str; else { var iLen = String(str).length; return String(str).substring(iLen, iLen - n); }}