const shoppingList = function(paniers) {
  const panierObject = {};
  for (let i = 0; i < paniers.length; i++) {
    for (let j = 0; j < paniers[j].length; j++) {
      let fruit = paniers[i][j];
        if (panierObject[fruit] === undefined) {
          panierObject[fruit] = 1;
        } else {
          panierObject[fruit] += 1;
        }
    }
  } return panierObject;
}


shoppingList([
    ["orange", "orange", "kiwi", "ananas"],
    ["kiwi", "ananas", "banane", "prune"],
    ["orange", "orange", "orange", "orange"],
    ["orange", "orange", "kiwi", "kiwi"],
    ["prune", "banane", "pamplemousse", "ananas"]
]);