jsBCrypt is an implementation of BCrypt written in JavaScript.

It uses Components of the Clipperz Javascript Crypto Library.

It is based upon jBCrypt

Usage Example:

var bcrypt = new bCrypt();
function crypt(password,rounds){
        try{
                var salt = bcrypt.gensalt(rounds);
        }catch(err){
                alert(err);
                return
        }
        try{
                var hash = bcrypt.hashpw(password, salt);
        }catch(err){
                alert(err);
                return;
        }
        alert(hash);
}

You can try a test instance of this here