Konami Code in Javascript/TypeScript

konami.js

function konami(callback) {
    var codes = [38, 38, 40, 40, 37, 39, 37, 39, 66, 65],
        position = 0;
    document.addEventListener('keydown', function (event) {
        if (event.keyCode === codes[position]) {
            position++;
            if (position === codes.length) {
                position = 0;
                callback();
            }
        } else {
            position = 0;
        }
    });
}

konami.ts

function konami(callback: () => void): void {
    let codes: number[] = [38, 38, 40, 40, 37, 39, 37, 39, 66, 65],
        position: number = 0;
    document.addEventListener('keydown', function (event: KeyboardEvent): void {
        if (event.keyCode === codes[position]) {
            position++;
            if (position === codes.length) {
                position = 0;
                callback();
            }
        } else {
            position = 0;
        }
    });
}