Node.js Raw Mode with Keystrokes

By  on  

I find the stuff that people are doing with Node.js incredibly interesting.  You here about people using Node.js to control drones, Arduinos, and a host of other devices.  I took advantage of Node.js to create a Roku Remote, a project that was fun and easier than I thought it would be.  There was one piece of this experiment that was difficult, however:  listening for keystrokes within the same shell that executed the script.

The process for using the remote is as follows:

  1. Execute the script to connect to your Roku:  node remote
  2. In the same shell, use arrow keys and hot keys to navigate the Roku
  3. Press CONTROL+C to kill the script

The following JavaScript code is what I needed to use to both listen for keystrokes within the same shell once the script had been started:

// Readline lets us tap into the process events
const readline = require('readline');

// Allows us to listen for events from stdin
readline.emitKeypressEvents(process.stdin);

// Raw mode gets rid of standard keypress events and other
// functionality Node.js adds by default
process.stdin.setRawMode(true);


// Start the keypress listener for the process
process.stdin.on('keypress', (str, key) => {

    // "Raw" mode so we must do our own kill switch
    if(key.sequence === '\u0003') {
        process.exit();
    }

    // User has triggered a keypress, now do whatever we want!
    // ...

});

The code above turns your Node.js script into an active wire for listening to keypress events.  With my Roku Remote, I pass arrow and letter keypress events directly to the Roku via a REST API (full code here).  I love that Node.js made this so easy -- another reason JavaScript always wins!

Recent Features

  • By
    Responsive and Infinitely Scalable JS Animations

    Back in late 2012 it was not easy to find open source projects using requestAnimationFrame() - this is the hook that allows Javascript code to synchronize with a web browser's native paint loop. Animations using this method can run at 60 fps and deliver fantastic...

  • By
    How to Create a RetroPie on Raspberry Pi – Graphical Guide

    Today we get to play amazing games on our super powered game consoles, PCs, VR headsets, and even mobile devices.  While I enjoy playing new games these days, I do long for the retro gaming systems I had when I was a kid: the original Nintendo...

Incredible Demos

  • By
    JavaScript Copy to Clipboard

    "Copy to clipboard" functionality is something we all use dozens of times daily but the client side API around it has always been lacking; some older APIs and browser implementations required a scary "are you sure?"-style dialog before the content would be copied to clipboard -- not great for...

  • By
    Scrolling “Agree to Terms” Component with MooTools ScrollSpy

    Remember the good old days of Windows applications forcing you to scroll down to the bottom of the "terms and conditions" pane, theoretically in an effort ensure that you actually read them? You're saying "No David, don't do it." Too late -- I've done...

Discussion

  1. Haldun

    I like a lot that you are writing about messing with Iot using nodejs! Looking forward to see more! Thanks!

Wrap your code in <pre class="{language}"></pre> tags, link to a GitHub gist, JSFiddle fiddle, or CodePen pen to embed!