Node.js Express middleware: app.param vs app.use

Question

In the chain of calls inside Express middleware, do the app.param methods always get called before app.use?

Answer 1

I tested with this program changing the order of app.use vs app.param with express 4.10.2. The param always runs first, which makes sense because the route handler expects to be able to do req.params.foo and in order for that to work the param handlers need to have run.

var express = require('express');
var app = express();

app.use("/:file", function (req, res) {
  console.log("@bug route", req.params.file);
  res.send();
});

app.param("file", function (req, res, next, val) {
  console.log("@bug param", val);
  next();
});



app.listen(3003);

Run this and test with curl localhost:3003/foo and you get the output:

@bug param foo
@bug route foo