Vanilla JS Konami Code

konami.js

var user_keys = [],
    konami = '38,38,40,40,37,39,37,39,66,65';
document.onkeydown = function(e){
    user_keys.push(e.keyCode)

    if (user_keys.toString().indexOf(konami) >= 0) {
        console.log('KONAMI!');
        user_keys = [];
    }
}