let haveItList = ['apples', 'milk', 'bread', 'peanutbutter'];
let wishList = ['cookies', 'bread', 'jam', 'peanutbutter', 'bananas', 'cheese'];
let inBothLists = wishList.filter(element => haveItList.includes(element));
// inBothLists = ['apples', 'bread', 'peanutbutter'];