All API calls need to be sent to http://localhost:14266 via a POST HTTP request. The data which will be sent is a JSON object which is defined by the following scheme:
Additional parameters are simply added as additional key-value pairs. If the command is successfully executed, your requested information is returned as either an object or a stringified object (use json.parse or equivalent to turn it into an object).
When making a request, make sure that the HTTP library you're using defines the Content-Length of the data to be sent. If this is not done automatically, manually add it via a header field e.g. 'Content-Length': Buffer.byteLength(JSON.stringify(command)).