Message d'erreur cannot read property 'box' of undefined"

var box = document.querySelector('.carouselbox');
   var next = box.querySelector('.next');
   var prev = box.querySelector('.prev');
   var items = box.querySelectorAll('.content li');
 
   var carousel = {
       counter: 0
       , amount: items.length
       , current: items[0]
       , navigate: function (direction) {
           carousel.current.classList.remove('current');
           carousel.counter = carousel.counter + direction;
           if (direction === -1 && carousel.counter < 0) {
               carousel.counter = carousel.amount - 1;
           }
           if (direction === 1 && !items[carousel.counter]) {
               carousel.counter = 0;
           }
           carousel.current = items[carousel.counter];
           carousel.current.classList.add('current');
       }
       , nexte: function () {
           next.addEventListener('click', function (e) {
               carousel.navigate(1);
           });
       }
       , preve: function () {
           prev.addEventListener('click', function (e) {
               carousel.navigate(-1);
           });
       }
       , clavier: function () {
           document.addEventListener("keydown", function (e) {
               if (e.keyCode === 37) {
                   carousel.navigate(-1);
               }
               else if (e.keyCode === 39) {
                   carousel.navigate(1);
               }
           });
       }
   , };
 
carousel.navigate(0);
   carousel.nexte();
   carousel.preve();
   carousel.clavier();