express-unless

What is express-unless?

The express-unless package is a middleware for Express.js that allows you to conditionally skip other middleware based on certain criteria. This is useful for scenarios where you want to apply middleware to most routes but exclude certain ones based on conditions like the request path, HTTP method, or custom logic.

What are express-unless's main functionalities?

Path-based exclusion

This feature allows you to exclude certain paths from the middleware. In this example, the middleware is applied to all routes except '/public' and '/about'.

const express = require('express');
const unless = require('express-unless');
const app = express();

const myMiddleware = (req, res, next) => {
  // Middleware logic
  next();
};

myMiddleware.unless = unless;

app.use(myMiddleware.unless({ path: ['/public', '/about'] }));

app.get('/public', (req, res) => res.send('Public Page'));
app.get('/about', (req, res) => res.send('About Page'));
app.get('/private', (req, res) => res.send('Private Page'));

app.listen(3000, () => console.log('Server running on port 3000'));

Method-based exclusion

This feature allows you to exclude certain HTTP methods from the middleware. In this example, the middleware is applied to all routes except those using the GET and POST methods.

const express = require('express');
const unless = require('express-unless');
const app = express();

const myMiddleware = (req, res, next) => {
  // Middleware logic
  next();
};

myMiddleware.unless = unless;

app.use(myMiddleware.unless({ method: ['GET', 'POST'] }));

app.get('/test', (req, res) => res.send('GET request'));
app.post('/test', (req, res) => res.send('POST request'));
app.put('/test', (req, res) => res.send('PUT request'));

app.listen(3000, () => console.log('Server running on port 3000'));

Custom logic exclusion

This feature allows you to exclude middleware based on custom logic. In this example, the middleware is skipped if the request contains a header 'x-custom-header' with the value 'skip'.

const express = require('express');
const unless = require('express-unless');
const app = express();

const myMiddleware = (req, res, next) => {
  // Middleware logic
  next();
};

myMiddleware.unless = unless;

app.use(myMiddleware.unless((req) => {
  return req.headers['x-custom-header'] === 'skip';
}));

app.get('/test', (req, res) => res.send('Test route'));

app.listen(3000, () => console.log('Server running on port 3000'));

Other packages similar to express-unless

express-conditional-middleware

The express-conditional-middleware package allows you to conditionally apply middleware based on custom conditions. It is similar to express-unless but focuses more on applying middleware conditionally rather than skipping it. This package is useful if you need more control over when middleware should be applied.

README

Conditionally skip a middleware when a condition is met.

Install

npm i express-unless --save

Usage

With existing middlewares:

var { unless } = require("express-unless");

var static = express.static(__dirname + "/public");
static.unless = unless;

app.use(static.unless({ method: "OPTIONS" }));

If you are authoring a middleware you can support unless as follow:

module.exports = function (middlewareOptions) {
  var mymid = function (req, res, next) {};

  mymid.unless = require("express-unless");

  return mymid;
};

Current options

• method it could be an string or an array of strings. If the request method match the middleware will not run.
• path it could be an string, a regexp or an array of any of those. It also could be an array of object which is url and methods key-pairs. If the request path or path and method match, the middleware will not run. Check Examples for usage.
• ext it could be an string or an array of strings. If the request path ends with one of these extensions the middleware will not run.
• custom it must be a function that accepts req and returns true / false. If the function returns true for the given request, the middleware will not run.
• useOriginalUrl it should be true or false, default is true. if false, path will match against req.url instead of req.originalUrl. Please refer to Express API for the difference between req.url and req.originalUrl.

Examples

Require authentication for every request unless the path is index.html.

app.use(
  requiresAuth.unless({
    path: ["/index.html", { url: "/", methods: ["GET", "PUT"] }],
  })
);

Avoid a fstat for request to routes doesnt end with a given extension.

app.use(
  static.unless(function (req) {
    var ext = url.parse(req.originalUrl).pathname.substr(-4);
    return !~[".jpg", ".html", ".css", ".js"].indexOf(ext);
  })
);

License

MIT 2014 - Jose Romaniello