keylistener-tampermonkey.js

// ==UserScript==
// @name         Generic Key Listener
// @namespace    http://tampermonkey.net/
// @version      0.1
// @description  logs key events. useful for creating a script you want actived on a set of keys
// @author       Petalousa
// @include        *
// @grant        none
// ==/UserScript==

/*
Handles the keyDown events
*/
let onKeyDown = (e) => {

    /*
    0 = off
    1 = on

    keyCodeObject outputs the event object of the KeyEvent
    keyCode outputs the keyCode of the key thats been pressed
    */
    let log = {keyCodeObject: 0, keyCode: 0}


    let keyAlt = e.altKey;
    let keyCtrl = e.ctrlKey;
    let keyShift = e.shiftKey;

    if(log.keyCodeObject){console.log(e);}

    // https://unixpapa.com/js/key.html
    // get the code representation of the key pressed.
    let keyCode = e.which === 0 ? e.charCode : e.keyCode;

    if(log.keyCode){console.log(keyCode);}

    // add cases for keys you want, and hook them up to functions
    switch(keyCode){
        case 221: // match ']' key
            yourFunctionHere();
            break;

        case 220: // match '\' key
            if(keyShift){
                console.log(`shift + \\ was pressed`);
            }else if (keyAlt){
                console.log(`alt + \\ was pressed`);
            }else if (keyCtrl){
                console.log(`ctrl + \\ was pressed`);
            }else{
                console.log(`just + \\ was pressed`);
            }
            break;
        default:
            //do nothing
    }
}

function yourFunctionHere(){
    console.log("things")
    // Your code here...
}

(function() {
    'use strict';
    document.addEventListener("keydown", onKeyDown);

    console.log("script loaded");
})();