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
    Send Text Messages with PHP

    Kids these days, I tell ya.  All they care about is the technology.  The video games.  The bottled water.  Oh, and the texting, always the texting.  Back in my day, all we had was...OK, I had all of these things too.  But I still don't get...

  • By
    7 Essential JavaScript Functions

    I remember the early days of JavaScript where you needed a simple function for just about everything because the browser vendors implemented features differently, and not just edge features, basic features, like addEventListener and attachEvent.  Times have changed but there are still a few functions each developer should...

Incredible Demos

  • By
    MooTools Star Ratings with MooStarRating

    I've said it over and over but I'll say it again:  JavaScript's main role in web applications is to enhance otherwise boring, static functionality provided by the browser.  One perfect example of this is the Javascript/AJAX-powered star rating systems that have become popular over the...

  • By
    The Simple Intro to SVG Animation

    This article serves as a first step toward mastering SVG element animation. Included within are links to key resources for diving deeper, so bookmark this page and refer back to it throughout your journey toward SVG mastery. An SVG element is a special type of DOM element...

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!