Node.js Interface Reference

// Import the readline module
const readline = require('readline');

// Create an Interface instance
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

const readline = require('readline');

// Create interface for reading from stdin and writing to stdout
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

// Ask a question and get the user's input
rl.question('What is your name? ', (name) => {
  console.log(`Hello, ${name}!`);

  // Ask another question
  rl.question('How are you today? ', (response) => {
    console.log(`Glad to hear: ${response}`);
    
    // Close the interface
    rl.close();
  });
});

// Handle the close event
rl.on('close', () => {
  console.log('Interface closed. Goodbye!');
});

// For Node.js v17 and above:
const readline = require('readline/promises');
const { stdin: input, stdout: output } = require('process');

async function askQuestions() {
  const rl = readline.createInterface({ input, output });

  try {
    // Ask questions sequentially
    const name = await rl.question('What is your name? ');
    console.log(`Hello, ${name}!`);

    const age = await rl.question('How old are you? ');
    console.log(`You are ${age} years old.`);

    const location = await rl.question('Where do you live? ');
    console.log(`${location} is a nice place!`);

    // Summary
    console.log('\nSummary:');
    console.log(`Name: ${name}`);
    console.log(`Age: ${age}`);
    console.log(`Location: ${location}`);
  } finally {
    // Make sure to close the interface
    rl.close();
  }
}

// Run the async function
askQuestions()
  .then(() => console.log('Questions completed!'))
  .catch(err => console.error('Error:', err));

const readline = require('readline');
const fs = require('fs');
const path = require('path');

// History file path
const historyFile = path.join(__dirname, '.command_history');

// Load command history if it exists
let commandHistory = [];
try {
  if (fs.existsSync(historyFile)) {
    commandHistory = fs.readFileSync(historyFile, 'utf8')
      .split('\n')
      .filter(cmd => cmd.trim());
  }
} catch (err) {
  console.error('Error loading history:', err.message);
}

// Create the interface with custom configuration
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: 'cli> ',
  historySize: 100,
  history: commandHistory
});

// Available commands
const commands = {
  help: () => {
    console.log('\nAvailable commands:');
    console.log('  help     - Show this help message');
    console.log('  hello    - Say hello');
    console.log('  date     - Show current date and time');
    console.log('  clear    - Clear the console');
    console.log('  exit     - Exit the CLI');
    rl.prompt();
  },
  hello: () => {
    console.log('Hello, world!');
    rl.prompt();
  },
  date: () => {
    console.log(new Date().toLocaleString());
    rl.prompt();
  },
  clear: () => {
    process.stdout.write('\x1Bc');
    rl.prompt();
  },
  exit: () => {
    // Save command history to file
    try {
      fs.writeFileSync(historyFile, rl.history.join('\n'));
      console.log(`Command history saved to ${historyFile}`);
    } catch (err) {
      console.error('Error saving history:', err.message);
    }
    
    console.log('Goodbye!');
    rl.close();
  }
};

// Display welcome message
console.log('Simple CLI Example');
console.log('Type "help" for available commands');

// Display the prompt
rl.prompt();

// Handle input
rl.on('line', (line) => {
  const input = line.trim();
  
  if (input === '') {
    rl.prompt();
    return;
  }
  
  const command = input.toLowerCase();
  
  if (commands[command]) {
    commands[command]();
  } else {
    console.log(`Command not found: ${input}`);
    console.log('Type "help" for available commands');
    rl.prompt();
  }
}).on('close', () => {
  process.exit(0);
});

// Handle Ctrl+C (SIGINT)
rl.on('SIGINT', () => {
  rl.question('Are you sure you want to exit? (y/n) ', (answer) => {
    if (answer.toLowerCase() === 'y') {
      commands.exit();
    } else {
      console.log('Operation cancelled');
      rl.prompt();
    }
  });
});

const readline = require('readline');

// Create the interface
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

// Function to prompt for masked input
function promptPassword(query) {
  return new Promise((resolve) => {
    // Create a hidden readline instance to control input/output
    const stdin = process.stdin;
    
    // Save the original configuration
    const originalStdinIsTTY = stdin.isTTY;
    if (originalStdinIsTTY) {
      stdin.setRawMode(true);
    }
    
    let password = '';
    
    // Write the query
    process.stdout.write(query);
    
    // Handle keypress events
    const onData = (key) => {
      // Ctrl+C
      if (key.toString() === '\u0003') {
        process.stdout.write('\n');
        process.exit();
      }
      
      // Enter key
      if (key.toString() === '\r' || key.toString() === '\n') {
        if (originalStdinIsTTY) {
          stdin.setRawMode(false);
        }
        stdin.removeListener('data', onData);
        process.stdout.write('\n');
        resolve(password);
        return;
      }
      
      // Backspace
      if (key.toString() === '\u0008' || key.toString() === '\u007f') {
        if (password.length > 0) {
          password = password.slice(0, -1);
          process.stdout.write('\b \b'); // Erase last character
        }
        return;
      }
      
      // Regular character
      password += key.toString();
      process.stdout.write('*'); // Show asterisk for each character
    };
    
    stdin.on('data', onData);
  });
}

// Example usage
async function login() {
  const username = await new Promise((resolve) => {
    rl.question('Username: ', (answer) => {
      resolve(answer);
    });
  });
  
  const password = await promptPassword('Password: ');
  
  console.log(`\nAttempting login for user: ${username}`);
  
  // Simulate authentication check
  if (username === 'admin' && password === 'password') {
    console.log('Login successful!');
  } else {
    console.log('Invalid username or password');
  }
  
  rl.close();
}

// Start the login process
login();

const readline = require('readline');

// Create the interface
const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});

// Menu options
const menuOptions = [
  { id: 1, name: 'View Profile' },
  { id: 2, name: 'Edit Settings' },
  { id: 3, name: 'Check Messages' },
  { id: 4, name: 'Log Out' },
  { id: 5, name: 'Exit' }
];

// Display the menu
function displayMenu() {
  console.log('\n===== MAIN MENU =====');
  menuOptions.forEach(option => {
    console.log(`${option.id}. ${option.name}`);
  });
  console.log('====================');
}

// Process the selected option
function processOption(option) {
  const selectedOption = menuOptions.find(item => item.id === parseInt(option));
  
  if (!selectedOption) {
    console.log('Invalid option. Please try again.');
    return promptUser();
  }
  
  console.log(`\nYou selected: ${selectedOption.name}`);
  
  // Handle each option
  switch (selectedOption.id) {
    case 1:
      console.log('Displaying user profile...');
      console.log('Name: John Doe');
      console.log('Email: john@example.com');
      console.log('Role: Administrator');
      break;
    case 2:
      console.log('Opening settings menu...');
      console.log('(Settings options would be displayed here)');
      break;
    case 3:
      console.log('Checking messages...');
      console.log('You have no new messages.');
      break;
    case 4:
      console.log('Logging out...');
      console.log('You have been logged out successfully.');
      return rl.close();
    case 5:
      console.log('Exiting the application...');
      return rl.close();
  }
  
  // Return to the menu after a short delay
  setTimeout(() => {
    promptUser();
  }, 1500);
}

// Prompt the user to select an option
function promptUser() {
  displayMenu();
  rl.question('Select an option: ', (answer) => {
    processOption(answer);
  });
}

// Start the menu
console.log('Welcome to the Interactive Menu Example');
promptUser();

// Handle close event
rl.on('close', () => {
  console.log('\nThank you for using the application!');
  process.exit(0);
});