keypress

What is keypress?

The keypress npm package is used to handle keyboard events in Node.js applications. It allows developers to listen for and respond to keypress events, making it useful for creating interactive command-line applications.

What are keypress's main functionalities?

Listening for Keypress Events

This feature allows you to listen for keypress events on the standard input. The code sample demonstrates how to set up the keypress listener and handle specific keypress events, such as Ctrl+C to exit the process.

const keypress = require('keypress');

// make `process.stdin` begin emitting 'keypress' events
keypress(process.stdin);

// listen for the 'keypress' event
process.stdin.on('keypress', function (ch, key) {
  console.log('got "keypress" event', key);
  if (key && key.ctrl && key.name == 'c') {
    process.stdin.pause();
  }
});

process.stdin.setRawMode(true);
process.stdin.resume();

Handling Special Keys

This feature allows you to handle special keys like arrow keys. The code sample demonstrates how to detect and respond to different arrow key presses.

const keypress = require('keypress');

// make `process.stdin` begin emitting 'keypress' events
keypress(process.stdin);

// listen for the 'keypress' event
process.stdin.on('keypress', function (ch, key) {
  if (key) {
    switch (key.name) {
      case 'up':
        console.log('up arrow key pressed');
        break;
      case 'down':
        console.log('down arrow key pressed');
        break;
      case 'left':
        console.log('left arrow key pressed');
        break;
      case 'right':
        console.log('right arrow key pressed');
        break;
    }
  }
});

process.stdin.setRawMode(true);
process.stdin.resume();

Other packages similar to keypress

readline

The readline package is a built-in Node.js module that provides an interface for reading data from a Readable stream (such as process.stdin) one line at a time. It can be used to handle keyboard input, but it is more focused on line-by-line input rather than individual keypress events. It is more suitable for applications that require reading and processing input line by line.

inquirer

Inquirer is a popular npm package for creating interactive command-line interfaces. It provides a higher-level abstraction for handling user input, including prompts, confirmations, and lists. While it can handle keypress events indirectly through its prompts, it is more focused on creating structured and user-friendly CLI interactions.

blessed

Blessed is a powerful library for creating terminal user interfaces. It provides a wide range of features for building complex and interactive terminal applications, including handling keypress events, creating widgets, and managing layouts. It is more comprehensive than keypress and is suitable for building full-fledged terminal applications.

README

keypress

Make any Node ReadableStream emit "keypress" events

Previous to Node v0.8.x, there was an undocumented "keypress" event that process.stdin would emit when it was a TTY. Some people discovered this hidden gem, and started using it in their own code.

Now in Node v0.8.x, this "keypress" event does not get emitted by default, but rather only when it is being used in conjuction with the readline (or by extension, the repl) module.

This module is the exact logic from the node v0.8.x releases ripped out into its own module.

Bonus: Now with mouse support!

Installation

Install with npm:

$ npm install keypress

Or add it to the "dependencies" section of your package.json file.

Example

Listening for "keypress" events

var keypress = require('keypress');

// make `process.stdin` begin emitting "keypress" events
keypress(process.stdin);

// listen for the "keypress" event
process.stdin.on('keypress', function (ch, key) {
  console.log('got "keypress"', key);
  if (key && key.ctrl && key.name == 'c') {
    process.stdin.pause();
  }
});

process.stdin.setRawMode(true);
process.stdin.resume();

Listening for "mousepress" events

var keypress = require('keypress');

// make `process.stdin` begin emitting "mousepress" (and "keypress") events
keypress(process.stdin);

// you must enable the mouse events before they will begin firing
keypress.enableMouse(process.stdout);

process.stdin.on('mousepress', function (info) {
  console.log('got "mousepress" event at %d x %d', info.x, info.y);
});

process.on('exit', function () {
  // disable mouse on exit, so that the state
  // is back to normal for the terminal
  keypress.disableMouse(process.stdout);
});

License

(The MIT License)

Copyright (c) 2012 Nathan Rajlich <[e-mail]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.