CODEWITHSUNDEEP
node.jsexpress
drmrbrewer
drmrbrewer

Reputation: 13069

node express: is path always optional?

According to the docs for express, the path parameter is optional for app.use, so to apply the middleware to any incoming request you can write:

app.use(function (req, res, next) {
  res.send('ANY request');
  next();
});

But for app.get the path parameter is apparently not optional, so to apply the middleware to any incoming GET request you have to write:

app.get('/', function (req, res, next) {
  res.send('GET request');
  next();
});

But I find that it doesn't complain if I do miss out the path:

app.get(function (req, res, next) {
  res.send('GET request');
  next();
});

So, are the above two definitions equivalent, or is the second one doing something different to the first one?

I'm also not sure of the difference between specifying / or * as the path:

app.get('*', function (req, res, next) {
  res.send('GET request');
  next();
});

So, in summary, is there any difference between app.get('/', fn) and app.get('*', fn) and app.get(fn)?

Upvotes: 0

Views: 73

Answers (1)

skirtle
skirtle

Reputation: 29132

Somewhat confusingly, there are two methods called app.get:

https://expressjs.com/en/4x/api.html#app.get

One is the converse to app.set, the other is the one for handling GET requests. In practice JS only allows a single method, so internally Express checks how many arguments are passed to work out which one you meant:

https://github.com/expressjs/express/blob/351396f971280ab79faddcf9782ea50f4e88358d/lib/application.js#L474

So while using app.get(fn) might not complain, it won't actually work as a route because it'll be treating it as the other form of get.

The difference between app.get('*', ...) and app.get('/', ...) is that the * will match any path whereas / will only match the exact path / (and nothing more). This is different from app.use, where the path is treated like a 'starts with'.

You may find the answer I gave here helpful to understand how paths differ between get and use: Difference between app.use and app.get *in proxying*.

Upvotes: 1

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