morgan

This is a Node.js module available through the npm registry. Installation is done using the npm install command. Create a new morgan logger middleware function using the given format and options. The format argument may be a string of a predefined name, a string of a format string, or a function that will produce a log entry. The format function will be called with three arguments tokens, req, and res, where tokens is an object with all defined tokens, req is the HTTP request and res is the HTTP response. The function is expected to return a string that will be the log line, or undefined / null to skip logging. Write log line on request instead of response. This means that a requests will be logged even if the server crashes, but data from the response (like the response code, content length, etc.) cannot be logged. To define a token, simply invoke morgan.token() with the name and a callback function.