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How to connect html to nodejs

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May 13, 2023 pm 05:10 PM

With the rapid development of web applications in recent years, Node.js (a lightweight JavaScript runtime environment) has also been widely used to develop various server-side applications. HTML is the core language on the web, so how to connect HTML to the Node.js backend? This article will answer them one by one for you.

In order to better understand the relationship between HTML and Node.js, you need to first understand how HTML works. HTML is the basic language for Web page design. It describes the structure and layout of the page through a large number of tags (tags), and displays content through various media files (such as images, sounds, and videos). Node.js is a back-end server technology based on JavaScript language, which can handle web requests and return web pages to the client. When a client requests a web page, Node.js retrieves the required data from the back-end database and then dynamically inserts it into the HTML code to generate a dynamic web page.

In order to realize the connection between HTML and Node.js, some frameworks and libraries need to be used to reduce the workload. The following are some commonly used frameworks and libraries:

1.Express.js

Express.js is a web application framework based on Node.js, which can help developers quickly build scalable web application. It provides a series of APIs to make application development easier.

The following is a simple example of using Express.js to connect HTML and Node.js:

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

app.use(express.static('public'));
app.get('/', (req, res) => {
  res.sendFile(__dirname + '/public/index.html');
});

app.listen(3000, () => {
  console.log('App listening on port 3000!');
});

In the above code, the express() function creates an Express application instance , and assign it to the app variable. The app.use() function specifies that the web server hosts static files (such as CSS and JavaScript files) in the public directory. The app.get() function specifies that when the URL path is /, the index.html file is sent from the server. app.listen()The function binds the application to port 3000.

2.Handlebars.js

Handlebars.js is a popular template engine that can generate HTML based on pages and data. It integrates very well with the Express.js framework for Node.js, with the help of which you can connect HTML and Node.js more conveniently.

The following is a simple example of using Handlebars.js to connect HTML and Node.js:

const express = require('express');
const exphbs  = require('express-handlebars');

const app = express();

app.engine('handlebars', exphbs());
app.set('view engine', 'handlebars');

app.get('/', (req, res) => {
  res.render('home', {
    name: 'World'
  });
});

app.listen(3000, () => {
  console.log('App listening on port 3000!');
});

In the above code, the exphbs() function returns a Handlebars.js instance , and assign it to the first parameter of the app.engine() function. app.set()The function specifies the template engine as Handlebars.js. app.get()The function renders the home.handlebars template when accessing the root path and passes the set name variable to "World".

3.Socket.IO

Socket.IO is a library for real-time communication between Node.js and the browser. It allows two-way communication between server and client, enabling real-time communication between HTML and Node.js.

The following is a simple example of using Socket.IO to connect HTML and Node.js:

Server code:

const express = require('express');
const app = express();
const server = require('http').createServer(app);
const io = require('socket.io')(server);

io.on('connection', (socket) => {
  console.log('a user connected');

  socket.on('disconnect', () => {
    console.log('user disconnected');
  });

  socket.on('chat message', (msg) => {
    console.log('message: ' + msg);
    io.emit('chat message', msg);
  });
});

server.listen(3000, () => {
  console.log('App listening on port 3000!');
});

Client code:

<!DOCTYPE html>
<html>
<head>
  <title>Socket.IO Example</title>
  <script src="/socket.io/socket.io.js"></script>
</head>
<body>
  <ul id="messages"></ul>
  <form id="message-form">
    <input type="text" id="message-input">
    <button type="submit">Send</button>
  </form>
  <script>
    var socket = io();

    var form = document.getElementById('message-form');
    form.addEventListener('submit', function(e) {
      e.preventDefault();
      var msgInput = document.getElementById('message-input');
      socket.emit('chat message', msgInput.value);
      msgInput.value = '';
    });

    socket.on('chat message', function(msg) {
      var messages = document.getElementById('messages');
      var message = document.createElement('li');
      message.innerHTML = msg;
      messages.appendChild(message);
    });
  </script>
</body>
</html>

In the above code, the server code uses the socket.io module to create a Socket.IO server and records logs when a connection is established between the client and the server. When receiving the chat message message from the client, the server broadcasts the message to all currently connected clients. The client uses the socket.io.js library to connect to the Socket.IO server, the form submission data is sent to the Socket.IO server, and the broadcast messages are automatically received through the Socket.IO client.

In summary, the connection between HTML and Node.js can achieve flexibility and real-time development of web applications. While using frameworks and libraries can make connecting easier, it's important to have a deep understanding of HTML, Node.js, and web development.

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