How to get arguments of another function? [duplicate]

I am trying to make a Express.js package that automatically generates routes from a object.

For example, if I were to put this in,

  info: {
    name: "Test",
    version: "V1.0.0",
    config: {
      platform: "express.js"
    }
  },
  users: {
    add: async function(firstName,lastName,email) {
      return email
    }
  }
}

then example.com/info/version would return V1.0.0.

That part I have already created successfully, but now I want to do the same for functions. I figure that I can pull arguments from query strings or bodies of POST requests and match them up with function arguments.

So now I need to find a way to get a function’s arguments, more specifically the argument names.

What I mean is that for the users.add function, I’d ideally like a array of arguments like ['firstName','lastName','email'] to be returned automatically.