esp8266webserver question: How to run some own code before server.serveStatic();

How do I run some own code before `server.serveStatic();` ?

I have a html file stored in LittleFS and serve it via `httpServer.serveStatic("/action", LittleFS, "/action.html");`
Now I want to execute some code first when someone requests `/action` and then send `action.html` , but I can't find no other way than to write a handler function that executes my code and then reads the file into a `String fileBuffer` and finally sending the String via `httpServer.send(200, HTML, fileBuffer);`

Does anybody has a hint for a better way of doing this?

I'using latest version of esp8266webserver on an wemos d1 mini with 4MB.