How to use nodejs in web pages

Node.js is a JS runtime environment that allows JS to run independently of the browser. In web development, it is often necessary to use Node.js to handle some background logic, such as processing form data, calling APIs, obtaining database information, etc. This article explains how to use Node.js in web pages.

First, you need to install Node.js on your computer. The latest stable version can be downloaded from the official Node.js website. After the installation is complete, you can run the following command on your computer to check whether the installation is successful:

node -v

If the version number of Node.js is returned, the installation is successful.

To use Node.js in a web page, you need to use a module system in Node.js, called CommonJS. In Node.js, every JS file can be referenced as a module. The module system exposes the contents of modules through module.exports and introduces the contents of other modules through the require() function.

// Greeting.js
function sayHello() {
  console.log('Hello, World!');
}

module.exports.sayHello = sayHello;

// index.js
const greeting = require('./Greeting');

greeting.sayHello();

In the above code, Greeting.js exposes the sayHello function through module.exports, and then uses require('./Greeting') in index.js to introduce the Greeting.js module and call the module sayHello function in .

To use Node.js in a web page, you need to use a package manager, called npm. npm is the package manager that comes with Node.js and is one of the largest software registries in the world. npm can help us manage the third-party packages that the project depends on, and install and configure them locally.

You can initialize an npm project locally through the following command:

npm init

This command will create a package.json file, which contains project-related information and dependent third-party packages. .

In the process of using Node.js, you often need to use some commonly used third-party packages, such as Express.js, Mongoose, Socket.io, etc. These third-party packages can be installed through npm, for example:

npm install express

This command will install Express.js and save it to package.json.

In web projects, using Node.js often requires the use of the Express.js framework. Express.js is a web development framework based on Node.js that makes it easy to build web applications.

The following is a simple example of using Express.js:

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

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

app.listen(3000, function () {
  console.log('Example app listening on port 3000!');
});

In the above code, require is used to introduce the Express.js module, and then creates an Express.js application. Among them, the app.get() function is used to process GET requests, and the res.send() function is used to return a string. Finally, use the app.listen() function to listen on port 3000 and start the server.

In addition to Express.js, common third-party packages such as Socket.io for real-time communication, Mongoose for connecting to MongoDB database, etc. can be found on npm and installed through the npm install command.

In addition to the common uses mentioned above, Node.js can also be used to build command line tools, build cross-platform desktop applications, and more. In short, using Node.js in web development can help us implement more complex background logic and a more efficient development process.

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