Exploring the variance in utilizing middleware callbacks with express.js

Here's a basic Express app:

var express = require('express');
var app = express();
var router = express.Router();

function test (req, res, next) {

}

I'm currently exploring the differences in functionality between these two approaches:

router.use('/myRoute', test)

router.post('/myRoute', function (req, res) {

});

And:

router.post('/myRoute', test, function (req, res) {
});

After reviewing the documentation (https://expressjs.com/en/4x/api.html#middleware-callback-function-examples) and (https://expressjs.com/en/4x/api.html#router.use), I have yet to find a clear distinction. Could there really be none?

Answer №1

The example code provided illustrates a key difference:

router.use('/myRoute', test)

This means that the "test" function will be used for any request made to /myRoute, regardless of method (POST, PUT, GET, etc).

In contrast:

router.post('/myRoute', test, function (req, res) {
});

This specifically applies the "test" function only to POST requests made to /myRoute.

Essentially, the difference lies in whether you want to apply the function globally or to a specific route. The choice depends on the context and requirements of your application.

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