How to create custom middleware in express ?

How to skip a middleware in Express.js ?

Last Updated : 09 Apr, 2021

If we want to skip a middleware we can pass parameters to the middleware function and decide based on that parameter which middleware to call and which middleware to not call.

Prerequisite:

express.js: To handle routing.

Setting up environment and execution:

Step 1: Initialize node project
```
npm init
```
Step 2: Install required modules
```
npm install express
```

Example:

index.js

const express = require("express");
// const database = require('./sqlConnection');

const app = express();

// Start server on port 5000
app.listen(5000, () => {
  console.log(`Server is up and running on 5000 ...`);
});

// define middleware 1
let middleware1 = (req, res, next) => {

    // decide a parameter
    req.shouldRunMiddleware2 = false;

    console.log("Middleware 1 is running !");
    next();
}

// define middleware 2
let middleware2 = (req, res, next) => {
    if(!req.shouldRunMiddleware2) {
        console.log("Skipped middleware 2");
        return next();
    }

    console.log("Middleware 2 is running !");
}

// define middleware 3
let middleware3 = (req, res, next) => {
    console.log("Middleware 3 is running !");
}

// create route for home page '/'
app.get("/", middleware1, middleware2, middleware3);

Output: Run the below command to start the server. After that go to http://localhost:5000 on browser to see output in console

node index.js

In browser.
Console:

How to create custom middleware in express ?

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