Keyboard controls for Crunchyroll's manga reader beta. I could have used Es6 easy, however, this should be good for majority of browsers. :)

crunchyrollMangaBetaKeyboardControls.js

function loadScript(url, callback){
    var script = document.createElement("script");
    script.type = "text/javascript";

    if (script.readyState){  // IEvil
        script.onreadystatechange = function () {
            if (script.readyState === "loaded" || script.readyState === "complete"){
                script.onreadystatechange = null;
                callback();
            }
        };
    } else {  // Real Browsers
        script.onload = function () {
            callback();
        };
    }

    script.src = url;
    document.getElementsByTagName("head")[0].appendChild(script);
}

// Load mousetrap for cross-browser keybindings
loadScript("https://craig.global.ssl.fastly.net/js/mousetrap/mousetrap.min.js", function () {
    console.log('Crunchyroll Manga Beta Controls by Brian Jemilo II Loaded!!!');
    
    Mousetrap.bind(['left', 'down'], function () {
        document.getElementsByClassName('type-next')[0].click();
    });
    
    Mousetrap.bind(['right', 'up'], function () {
        document.getElementsByClassName('type-prev')[0].click();
    });
});