xtermjs Tutorial – Implement bash commands

xterm.js is a powerful library that enables developers to integrate a fully functioning terminal within web applications. It’s a component that emulates the functionality of terminal right inside your web pages. This xtermjs tutorial will guide you through the basics of using xterm.js, setting up a terminal in your HTML, and implementing simple bash commands like echo and cat.

Table of Contents

• Setting Up xterm.js
• Implementing Basic Bash Commands
• Troubleshooting Tips
• References
• Summary

Setting Up xterm.js

Firstly, let’s set up xterm.js in your web project:

1. Add the xterm.css file to the head of your HTML to style the terminal

   <link rel="stylesheet" href="https://unpkg.com/xterm/css/xterm.css" />

    

2. Create a basic web page with a <div> element as a container for the terminal:

   <div id="terminal"></div>
   

    

3. Next, include the xterm.js script in your HTML before the closing </body> tag:

<script src="https://unpkg.com/xterm/lib/xterm.js"></script>

Now, let’s write the code to initialize xterm.js:

const term = new Terminal();
const terminalContainer = document.getElementById('terminal');
term.open(terminalContainer);
term.write('Welcome to Xterm.js Demo\n');

Implementing Basic Bash Commands

To handle basic commands like echo and cat, you can use xterm.js’s onData event to listen for user input and respond appropriately. Below is the code that demonstrates handling these two commands:

let command = '';

term.onData(e => {
    if (e === '\r') { // Enter key
        handleCommand(command.trim());
        command = ''; // Reset command buffer
    } else if (e === '\x7F') { // Backspace key
        if (command.length > 0) {
            term.write('\b \b'); // Move cursor back, erase character, move cursor back again
            command = command.slice(0, -1); // Remove last character from command buffer
        }
    } else {
        term.write(e); // Echo the typed character
        command += e; // Add typed character to command buffer
    }
});

function handleCommand(input) {
    const args = input.split(' ');
    const command = args[0];
    const params = args.slice(1).join(' ');

    switch (command) {
        case 'echo':
            term.write(params + '\n');
            break;
        case 'cat':
            // Implement 'cat' command logic here
            break;
        default:
            term.write(`Command not found: ${command}\n`);
    }
}

In this code:

• term.onData() listens for each character input by the user.
• If the user presses Enter (\r), it triggers the handleCommand() function with the accumulated command string.
• If the user presses Backspace (\x7F), it removes the last character from the command string and erases the character from the terminal.
• Otherwise, it echoes the typed character and adds it to the command string.

Troubleshooting Tips

• If the terminal doesn’t show up, check that you’ve included the xterm.css file correctly and that there are no JavaScript errors in the browser console.
• Ensure the container <div> is present in the HTML and is not hidden or removed by JavaScript before initializing the terminal.

• When implementing custom command handling, ensure that you correctly trim and compare the command strings.

References

• xterm.js GitHub repository
• xterm.js Official Documentation

Summary

In this xtermjs tutorial, we’ve covered how to set up xterm.js in an HTML environment, provided a simple example of initializing a terminal, and demonstrated how to implement basic bash commands using the onData event. xterm.js is an incredibly versatile library that can enhance your web applications with terminal functionality, and with continued exploration, you can even integrate it with backend systems for more complex operations.