Controlling a RC Car by connecting BOLT to Arduino

I am trying to control a car by connecting IOT BOLT to Arduino. For this I need to send a character to BOLT via internet and BOLT sends this to Arduino . The Arduino code is working fine but it is not receiving the right character from BOLT.
I wrote the following code to send a character to BOLT. F makes the car go forward and S makes the car stop.

     <button onclick="serialWrite?data='F'" >FORWARD</button>
     <button onclick="serialWrite?data='S'">STOP</button>


I do not understand how to use the controller.js file. How do I link two files to the device?

Is the code is correct

I don’t know. That’s why I am asking . This code doesn’t send the characters I want to send to Arduino.

I hope your doubt must have been solved by now, but still writing it so that it can help someone else facing the same problem

If you are downloading the code, then the .htm and .js file must be in the same place for the code to work. But if you are writing the entire code in the Bolt cloud in a product, then you need to make an html file, copy the contents of htm file in it. Then make a tag and write the javascript code in between the tag.
Hope this helps.