ES6 for循环的三种方法

ES6 for循环的三种方法

// 1.普通for循环
let totalPrice1 = 0;
for (let i = 0; i < books.length; i++) {
  totalPrice1 += books[i].count * books[i].price
}
console.log(totalPrice1);

// 2. for(let i in this.books),i是下标
let totalPrice2 = 0;
for (let i in books) {
  let book = books[i];
  totalPrice2 += book.count * book.price
}
console.log(totalPrice2);

// 3. for(let item of  books)
let totalPrice3 = 0;
for (let item of books) {
  totalPrice3 += item.count * item.price
}
console.log(totalPrice3);