Array to key/value JSON conversion
Not sure that a class definition makes a lot of sense here since you don’t really have any real behavior being defined in this class. 
Destructuring can also help you populate variables from the input array directly.
camelCase is generally preferred in JS vs. snake_case. 


For example you might simplify to something like this:

const conversionFn = ( [ channelId, payload, sequence ] ) =&gt; {  
  return { channelId, payload, sequence };
};