Is binary hashing possible in javascript front end

I want to create an HOTP client using javascript similar to SpeakEasy

The above library is intended for server side javascript usage and it uses NodeJS.

I want to do the same thing on front end javascript in a browser but I haven't been able to use CryptoJS to achieve this behavior.

         var key = "abc";
         var counter = "123";

         // create an octet array from the counter
         var octet_array = new Array(8);

         var counter_temp = counter;

         for (var i = 0; i < 8; i++) {
             var i_from_right = 7 - i;

             // mask 255 over number to get last 8
             octet_array[i_from_right] = counter_temp & 255;

             // shift 8 and get ready to loop over the next batch of 8
             counter_temp = counter_temp >> 8;
         }

        // There is no such class called as Buffer on Browsers (its node js)
         var counter_buffer = new Buffer(octet_array);

         var hash = CryptoJS.HmacSHA1(key,counter_buffer);

         document.write("hex value "+ hash);
         document.write("hash value "+    CryptoJS.enc.Hex.stringify(hash));