Installing Express 5 and Project Setup

What you will learn

How to create a new project folder and package.json for an Express app
How to install Express 5 and check that you really got version 5
How to set up "type": "module", npm scripts and a .gitignore file
A simple folder structure that will grow with you through the course
How to fix the most common setup errors

In the last lesson you installed Node.js and npm. Now you will turn an empty folder into a ready-to-code Express 5 project. By the end you will have a tiny server running, as a quick check that everything works.

Step 1: Create the project folder

Every project lives in its own folder. Open a terminal and run:

mkdir my-express-app
cd my-express-app

mkdir makes the folder and cd moves your terminal into it. From now on, every command in this lesson runs inside my-express-app.

Tip: Open this folder in your code editor too. In VS Code use File > Open Folder, or type code . in the terminal (the . means “the current folder”).

Step 2: Create package.json

npm init -y

This creates package.json, the ID card of your project. The -y flag accepts all the default answers so you don’t have to type them.

Step 3: Switch on ES modules

This course writes code with import and export, the modern JavaScript module syntax called ES modules (ESM). Node.js needs to be told to use it. The quickest way is this npm command:

npm pkg set type=module

npm pkg set edits package.json for you. It adds (or changes) this line:

{
  "type": "module"
}

You could also open package.json and type the line yourself. Both ways give the same result. The ES Modules vs CommonJS lesson explains the older require() style and why this line matters.

Step 4: Install Express

Here is the main event:

npm install express

npm downloads Express and everything Express itself depends on into node_modules. It also adds Express to package.json:

{
  "dependencies": {
    "express": "^5.1.0"
  }
}

Your number may be higher than the one shown here. What matters is that it starts with 5. Express 5 has been the default (“latest”) version on npm since 2025, so a plain npm install express gives you Express 5.

Check the installed version

The number in package.json is a range (^5.1.0 means “5.1.0 or any newer 5.x”). To see the exact version that is installed, ask npm:

npm ls express

my-express-app@1.0.0 /Users/asha/my-express-app
└── express@5.1.0

Warning: If you see express@4.x.x, you are not on Express 5. This usually happens when you copy an old package.json that pins "express": "^4.x". Fix it with npm install express@5. Many older tutorials online use Express 4, and a few of their patterns no longer work in Express 5.

Step 5: Look at what you have

Your folder now looks like this:

my-express-app/
├── node_modules/        downloaded packages (do not edit, do not commit)
├── package.json         project info, dependencies, scripts
└── package-lock.json    exact installed versions (commit this)

Open node_modules and you will find many folders, not just express. Express is built from smaller packages (for routing, cookies, body parsing and so on), and npm installs all of them. This is normal.

Step 6: Add a .gitignore file

Git is a tool that tracks changes to your code. Even if you don’t use Git yet, add this file now so you never accidentally share huge or secret files later. Create a file named .gitignore (the name starts with a dot):

# .gitignore
node_modules/
.env
*.log

Each line is a pattern Git should ignore:

node_modules/ can always be rebuilt with npm install.
.env will hold secrets such as passwords. You will create it in Environment Variables and Configuration.
*.log ignores any log files.

Step 7: Add npm scripts

Open package.json and replace the "scripts" section so it looks like this:

{
  "name": "my-express-app",
  "version": "1.0.0",
  "type": "module",
  "main": "server.js",
  "scripts": {
    "start": "node server.js",
    "dev": "node --watch server.js"
  },
  "dependencies": {
    "express": "^5.1.0"
  }
}

npm start runs the server normally. Hosting providers often use this exact command.
npm run dev runs it in watch mode: Node.js restarts the server whenever you save a file. This needs Node.js 18.11 or newer, and you will learn all about it in The Dev Loop: node –watch and Nodemon.

Note: Your package.json may have extra fields such as "description", "keywords" or "author". Leave them; they don’t affect anything here.

Step 8: A quick smoke test

A smoke test is a tiny check that something basically works, before you build on it. Create server.js next to package.json:

// server.js
import express from 'express';

const app = express();

app.get('/', (req, res) => {
  res.send('Express 5 is installed and working!');
});

app.listen(3000, (error) => {
  if (error) throw error;
  console.log('Server running on http://localhost:3000');
});

Start it:

npm start

> my-express-app@1.0.0 start
> node server.js

Server running on http://localhost:3000

Now open http://localhost:3000 in your browser. You should see the message. You can also test from a second terminal window (the first one is busy running the server):

curl http://localhost:3000

Express 5 is installed and working!

Press Ctrl + C in the server’s terminal to stop it. Don’t worry about understanding every line yet; the next lesson explains this file piece by piece.

Note: On Windows PowerShell, type curl.exe instead of curl. Plain curl there runs a different built-in command.

A folder structure that will grow with you

Right now one file is enough. As the course goes on, you will split code into folders. Here is where you are heading, so the names won’t surprise you later:

my-express-app/
├── src/
│   ├── app.js           creates and configures the Express app
│   ├── routes/          one file per group of URLs (users, posts...)
│   ├── middleware/      reusable request helpers
│   └── controllers/     the logic for each route
├── public/              images, CSS and other static files
├── server.js            starts the server (calls app.listen)
├── .env                 secrets and settings (never committed)
├── .gitignore
└── package.json

You do not need to create all of this now. Create folders when a lesson asks for them. Keeping app.js (the app) separate from server.js (the part that listens on a port) is a habit you will start in the next lesson; it makes testing much easier later.

Adding Express to an existing project

Already have a Node.js project? You only need two steps inside its folder:

npm install express
npm ls express

If the project was on Express 4, npm install express@5 upgrades it. Upgrading old code is covered in detail in Migrating from Express 4 to Express 5.

Common mistakes

Common mistake: SyntaxError: Cannot use import statement outside a module. Node.js is treating your file as the older CommonJS style. Make sure package.json contains "type": "module" and that you are running the file from the project folder.

Common mistake: Error: Cannot find module 'express'. Express is not installed in this folder. Check you are in the right folder with pwd, then run npm install express.

Common mistake: npm error enoent Could not read package.json. You ran npm start (or another npm script) outside your project folder. cd into the folder that contains package.json and try again.

Common mistake: Naming your own file express.js. It can confuse you and your tools about which “express” you mean. Use server.js or app.js.

Common beginner questions

Do I need to install Express globally? No. Express is a library your code imports, so it must be installed in each project with plain npm install express.

Can I delete node_modules? Yes, any time. Run npm install to get it back exactly as before, thanks to package-lock.json.

What about the express-generator tool I see in tutorials? It creates a starter project for you, but it is old and its output does not match how this course writes code. Building the project by hand, as you just did, teaches you what every file is for.

Key takeaways

A new project is three commands: mkdir, npm init -y, and npm install express.
npm pkg set type=module lets you use import and export in your files.
npm ls express shows the exact installed version. It should start with 5.
Add a .gitignore with node_modules/ and .env from day one.
"start" and "dev" npm scripts give you short, standard commands for running the server.

Practice

Create a second project called practice-app from scratch, without looking at this lesson. Check the Express version with npm ls express.
Change the message in server.js, stop the server with Ctrl + C, start it again, and confirm the new message appears with curl.
Try npm run dev, change the message again and save. Watch the terminal: what happens?
Delete node_modules, run npm start, and read the error. Then fix it with npm install.

What’s next

You have a working project. Now let’s understand exactly what each line of that server does. Continue with Your First Server and app.listen.