Is there a difference between these two methods of using express middleware?

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I have come across two different ways to define express, use() middleware and am wondering if there is any difference between them or if it is simply syntax sugar?

const app = express();
const app = express();

They are not two ways of using it. They are the same way. By calling app.use().

And it is not syntactic sugar either. app.use() returns this, hence the value it returns (which is the same value stored in app) can be used to chain another call of .use() and so on. The result is the same; it's a matter of taste which way you prefer (you should use the one that you feel it's easier to read and understand).

Using Express middleware, An Express application can use the following types of middleware: The example below defines two routes for GET requests to the /user/:id path. The second� Express provides us app.use() method which is specifically used to define middlewares. app.use() method may seem similar to app.all() but there are a lot of differences between them which makes app.use() perfect for declaring middlewares. Let’s see how app.use() method works: app.use() Here are the difference between app.use() and app.all

It's called method chaining:

Method chaining is a technique to simplify code in scenarios that involve performing multiple operations on the same object.

Looking into the source of Express.js and application:

app.use = function use(fn) {
  return this:

As you can see use returns this hence chaining is possible.

Writing middleware for use in Express apps, HTTP method for which the middleware function applies. Starting with Express 5, middleware functions that return a Promise will call next(value) when they� Using middleware. An Express application is essentially a series of middleware calls. Middleware is a function with access to the request object (req), the response object (res), and the next middleware in line in the request-response cycle of an Express application, commonly denoted by a variable named next.

There is no real difference, only one is 3 characters shorter each time you want to write "app.use". It's kind of like definining .ejs and the naming files "home" instead of "home.ejs". The difference is that you finish the line each time using ;

app.use(cors()); with ; is the end of the string.

For example if you used the below code, the .use(failureHandler); wouldn't work because the ; ends the first app.use

const app = express();
  .use(anotherHandler); <------- STOPS HERE

They'll both work fine, but in my experience it would be more noticable missing 1

";" rather than each ";" on each line.

I would say it's just sugar syntax as you've mentioned.

Build and Understand Express Middleware through Examples, Middleware literally means anything you put in the middle of one layer I'm using the latest version of both as of the time of this article, which is Let's take a look at a few more examples of the different types of middleware. The main difference between firmware and middleware is that the firmware is a type of software that allows controlling the device’s hardware while the middleware is a software that provides services to software applications beyond those available from the operating system.

Express Explained with Examples, Express is the most popular Node.js framework because it requires minimum setup to start an Both req and res are made available to us by the Express framework. It provides different methods for a client to make request. There is no functional difference between these two syntaxes. It’s just a matter of personal taste. Pre-Populated Data. Sample 1 started out with an empty pet store, so you had to add a pet before GET /pets would return any data. Now in Sample 2, we’re using the MemoryDataStore class to pre-populate the Mock middleware with data.

What is an Express Middleware and How to Create One, The next function is a function in the Express router which, when On every request these two middlewares will run- bodyParser will run first before the one below it by customMiddleware2 for the GET method on the path '/some/path' pass the request to the next middleware by using the next function. In most cases they would work equivalently. The biggest difference is the order in which middleware would be applied: app.all() attaches to the application's router, so it's used whenever the app.router middleware is reached (which handles all the method routes

Middleware in Express. When I was learning Express, the idea , In this scenario, the request starts off in the browser and… To understand how middleware works in Express, there's a few things you have to Consider a different scenario: two. If the callback is passed as the first argument to app.use () , it matches all routes. 19 ways to become a better Node.JS� TYPES OF MIDDLEWARE. As I mentioned earlier, the term middleware can be used to refer to any software that sits between two different applications. As such, there is a wide variety of what counts as middleware. However, middleware can still be classified into broad categories depending on their particular function.