initialize express app
Step 1: Install Express To initialize an Express app, you need to have Express installed in your project. You can install it by running the following command in your terminal:
npm install express
This command will install the Express package and its dependencies in your project.
Step 2: Create an Express app file
Next, create a new JavaScript file in your project directory. You can name it anything you want, but for this example, let's call it app.js
. Open the file in your preferred code editor.
Step 3: Import the Express module
In your app.js
file, import the Express module using the require
function:
const express = require('express');
This line imports the Express module and assigns it to the express
variable, which you can use to create and configure your Express app.
Step 4: Create an Express app
Create a new Express app by calling the express
function:
const app = express();
This line creates a new Express app and assigns it to the app
variable. You will use this variable to configure your app and define routes.
Step 5: Set up basic routes Next, you can set up some basic routes for your app. For example, you can define a route that responds with "Hello, World!" when someone accesses the root URL ("/"):
app.get('/', (req, res) => {
res.send('Hello, World!');
});
This code defines a GET route for the root URL ("/") using the app.get
method. When a user visits the root URL, the callback function is executed, which sends the response "Hello, World!" back to the client.
Step 6: Start the server
Finally, you need to start the server and listen for incoming requests. Add the following code at the end of your app.js
file:
const port = 3000; // or any other port number you prefer
app.listen(port, () => {
console.log(`Server is running on port ${port}`);
});
This code starts the server and listens for incoming requests on the specified port (in this example, port 3000). The callback function logs a message to the console indicating that the server is running.
That's it! You have now initialized an Express app and set up a basic route. You can continue configuring your app and defining more routes as needed.