Node.js pass variable to route

Question

I have very simple node.js noob question. How do I pass a variable to an exported route function?

Routes file

exports.gettop = function(n, req, res) {
  console.log(n);
  res.send(200);
};

Server file

app.get('/api/v1/top100', routes.gettop(100)); 

Error: .get() requires callback functions but got a [object Undefined]

Answer 1

For your example, you want to create a new function that will close around your value of n. In your case, you are executing gettop and passing the returned value to express as your route, which means gettop needs to return the route handler.

exports.gettop = function(n){
    return function(req, res) {
        console.log(n);
        res.send(200);
    };
};