JSFiddle - React, Tailwind, and code Playground

by David Thomas

CSS

body {
    height: 100%;
    background-color: #ffa;
}

JavaScript

// taken from: http://stackoverflow.com/a/14853974/82548
// attach the .equals method to Array's prototype to call it on any array
Array.prototype.equals = function (array) {
    // if the other array is a falsy value, return
    if (!array)
        return false;

    // compare lengths - can save a lot of time 
    if (this.length != array.length)
        return false;

    for (var i = 0, l=this.length; i < l; i++) {
        // Check if we have nested arrays
        if (this[i] instanceof Array && array[i] instanceof Array) {
            // recurse into the nested arrays
            if (!this[i].equals(array[i]))
                return false;       
        }           
        else if (this[i] != array[i]) { 
            // Warning - two different object instances will never be equal: {x:20} != {x:20}
            return false;   
        }           
    }       
    return true;
}   


var keyOrder = [37,38,39,40],
    keyPresses = [];

function keySequenceCheck (e) {
    keyPresses.push(e.keyCode);
    if (keyPresses.length > keyOrder.length) {
        keyPresses.shift();
    }
    
    if (keyPresses.equals(keyOrder)) {
        console.log('Message');
    }
}

document.body.addEventListener('keyup', keySequenceCheck);