When convert null to string it is better to return empty string then 'null' string; var a= null; var b= ''; b= 'test' + a; //b == 'testnull'; EXPECTED: b == 'test' -------------- next part -------------- An HTML attachment was scrubbed... URL: http://mail.mozilla.org/pipermail/es-discuss/attachments/20071011/908371f4/attachment-0002.html