How to capture the arrow keys in node.js

Question

What is the utf8 code for all four arrow keys (up down left right)?

I am learning node.js and I am trying to detect whenever these keys are being pressed.

He

Answer 1

This should solve your problem:

var stdin = process.stdin;
stdin.setRawMode(true);
stdin.resume();
stdin.setEncoding('utf8');

stdin.on('data', function(key){
    if (key == '\u001B\u005B\u0041') {
        process.stdout.write('up'); 
    }
    if (key == '\u001B\u005B\u0043') {
        process.stdout.write('right'); 
    }
    if (key == '\u001B\u005B\u0042') {
        process.stdout.write('down'); 
    }
    if (key == '\u001B\u005B\u0044') {
        process.stdout.write('left'); 
    }

    if (key == '\u0003') { process.exit(); }    // ctrl-c
});

This could also be of interest for you:

stdin.on('data', function(key){
    console.log(toUnicode(key)); //Gives you the unicode of the pressed key
    if (key == '\u0003') { process.exit(); }    // ctrl-c
});

function toUnicode(theString) {
  var unicodeString = '';
  for (var i=0; i < theString.length; i++) {
    var theUnicode = theString.charCodeAt(i).toString(16).toUpperCase();
    while (theUnicode.length < 4) {
      theUnicode = '0' + theUnicode;
    }
    theUnicode = '\\u' + theUnicode;
    unicodeString += theUnicode;
  }
  return unicodeString;
}

I found the function here: http://buildingonmud.blogspot.de/2009/06/convert-string-to-unicode-in-javascript.html