Nodejs builds website server

Node.js is a JavaScript runtime environment based on the Chrome V8 engine that can be used to build efficient web applications. With the development of Node.js in development, it has become a widely used back-end development tool. This article will introduce how to use Node.js to build a website server.

1. Install Node.js
First, before installing Node.js, check whether Node.js is installed on the computer and use the command "node -v" to view the installed version. If it is not installed, you can download the installation package from the Node.js official website and install it.

2. Create a project
Next, create a new folder myapp as the project folder, and use the command line tool to enter the folder. Next, entering the command "npm init" in the command line tool will generate a package.json file, which is used to store the basic information and dependent modules of the project.

3. Install Express
Express is a popular Node.js framework. Here we use the Express framework to build a web server. Enter the command "npm install express –save" in the command line tool to install the Express framework and save it to the project's dependency list. Next, we create an app.js file and enter the following code:

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

const port = 3000;

app.get('/', (req, res) => {
      res.send('Hello World!');
});

app.listen(port, () => {
      console.log(`Server running at http://localhost:${port}`);
});

This code uses the basic example of the express module to create an Express application. In your application, define the port number and listen for requests using the app.listen() method.

4. Run the application
Run the "node app.js" command on the command line, and the application will start listening for requests. Enter "http://localhost:3000" in the browser, and the server should return the text message "Hello World!"

5. Hosting static files
Hosting static files is very important for web development. We can use the middleware provided by the Express framework to host static resource files. Add the following code to the app.js file:

app.use(express.static('public'));

Among them, public is the name of the directory where static files are placed, and the files stored in this directory will be hosted on the server.

6. Use template engine
When you need to return dynamic HTML or views, you can use the template engine to generate it. The Express framework supports multiple template engines, such as Pug and EJS. Here we choose EJS template engine.

Enter the command "npm install ejs –save" on the command line to install the EJS template engine, and add the following code to the app.js file:

app.set('view engine', 'ejs');

Next, we can add it to the views folder Create an index.ejs file in the app.js file, and add the following code in the app.js file:

app.get('/users/:name', (req, res) => {
      res.render('index', { name: req.params.name });
});

Enter "http://localhost:3000/users/Jim" in the browser, you can see that it is returned "Hello Jim!" text message.

7. Using routing
Routing is a collection of paths and methods for accessing different pages of the website. You can use the Express framework to define and process routing. Add the following code in the app.js file:

app.get('/about', (req, res) => {
      res.send('This is about page');
});

app.post('/login', (req, res) => {
      res.send('This is login page');
});

When accessing the "/about" path or using the POST method to access the "/login" path, the server will return the corresponding response.

8. Using middleware
Middleware is located between the client and the server and can process requests, modify responses or perform other tasks. We can use the middleware provided by the Express framework to enhance the functionality of the application. The following is a simple middleware example, add the following code in the app.js file:

const myMiddleware = (req, res, next) => {
    console.log('This is my middleware');
    next();
};
app.use(myMiddleware);

We can add multiple middleware to extend the functionality of the application.

9. Use a database
For most websites, a database is essential. Node.js provides many popular database drivers such as Mongodb and MySQL, etc. Taking the MySQL driver as an example, enter the command "npm install mysql –save" in the command line tool to install the Mysql module.

Next, you can add the following code in the app.js file:

const mysql = require('mysql');

const connection = mysql.createConnection({
    host: 'localhost',
    user: 'root',
    password: '',
    database: 'mydb'
});

connection.connect((error) => {
    if (error) {
        console.log('Connection failed');
        return;
    }
    console.log('Connected successfully');
});

app.get('/users', (req, res) => {
    connection.query('SELECT * FROM users', (error, results, fields) => {
        if (error) {
            console.log('Failed to get users');
            return;
        }
        res.send(results);
    });
});

In this code, we connect to the local MySQL database and get all users from the users table and put the results return.

So far, we have successfully built a simple website server using Node.js and implemented some basic functions. Although this article is just an introductory tutorial, as you learn the Node.js and Express frameworks, developers can easily build more advanced web applications.

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