Which property on arrays can be used to loop through them in javascript code example

Example: looping through an object of objects with arrays

let storeItems = {   
    eggs: {
      price: 3.77, quantity: 30
    },   
                  
    milk: {
      price: 2.22, quantity: 23
    },   
                   
    butter: {
      price: 2.00, quantity: 22
    },       
                   
    carrots: {
      price: 3.00, quantity: 11
    },   
                   
    beef: {
      price: 6.18, quantity: 34
    },   
    chicken: {
      price: 5.44, quantity: 34
    }
  };
  
  for(let item in storeItems) {   
    console.log(`${storeItems[item].quantity} ${item}s each cost ${storeItems[item].price}`);
}
  
  
// //OUTPUT:“30 eggs each cost 3.77”
// “23 milks each cost 2.22”
// “22 butters each cost 2”
// “11 carrots each cost 3”
// “34 beefs each cost 6.18”
// “34 chickens each cost 5.44”