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
    39 Shirts – Leaving Mozilla

    In 2001 I had just graduated from a small town high school and headed off to a small town college. I found myself in the quaint computer lab where the substandard computers featured two browsers: Internet Explorer and Mozilla. It was this lab where I fell...

  • By
    How to Create a Twitter Card

    One of my favorite social APIs was the Open Graph API adopted by Facebook.  Adding just a few META tags to each page allowed links to my article to be styled and presented the way I wanted them to, giving me a bit of control...

Incredible Demos

  • By
    Create Twitter-Style Buttons with the Dojo Toolkit

    I love that JavaScript toolkits make enhancing web pages incredibly easy. Today I'll cover an effect that I've already coded with MooTools: creating a Twitter-style animated "Sign In" button. Check out this five minute tutorial so you can take your static...

  • By
    Printing MooTools Accordion Items

    Sometimes we're presented with unforeseen problems when it comes to our JavaScript effects. In this case, I'm talking about printing jQuery and MooTools accordions. Each "closed" accordion content element has its height set to 0 which means it will be hidden when the...

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!