Vue3基础篇之常用的循环示例详解

const list = reactive({ list: [] })
list.list = [
  { id: 1, name: 'jack', is_use: false },
  { id: 2, name: 'jacker', is_use: true }
]
for (let i = 0; i < list.list.length; i++) {
  if (list.list[i].is_use) {
    console.log(list.list[i].name)
  }
}

const plist = list.list.filter((i) => {
  return i.is_use
})

const books = [
  { title: 'Book A', pages: 90, price: 10.99, releaseYear: 2016 },
  { title: 'Book B', pages: 320, price: 18.99, releaseYear: 2011 },
  { title: 'Book C', pages: 250, price: 29.99, releaseYear: 2013 },
  { title: 'Book D', pages: 450, price: 24.99, releaseYear: 2009 },
  { title: 'Book E', pages: 650, price: 35.99, releaseYear: 2001 },
  { title: 'Book F', pages: 370, price: 22.99, releaseYear: 2014 },
  { title: 'Book G', pages: 520, price: 27.99, releaseYear: 2017 }
];
const filteredBooks = books.filter(book => {
  // 筛选条件1: 出版年份在2010年以后
  const isRecent = book.releaseYear > 2010;
  // 筛选条件2: 页数在300到600之间
  const isModerateLength = book.pages >= 300 && book.pages <= 600;
  // 筛选条件3: 价格低于或等于25美元
  const isAffordable = book.price <= 25;
  // 只有同时满足所有条件的书籍被返回
  return isRecent && isModerateLength && isAffordable;
});
console.log(filteredBooks);

const numbers = [1, 2, 3, 4, 5];
const doubled = numbers.map(number => number * 2);
console.log(doubled);  // [2, 4, 6, 8, 10]

const users = [
  { name: 'Alice', age: 22 },
  { name: 'Bob', age: 24 },
  { name: 'Charlie', age: 28 }
];
const names = users.map(user => user.name);
console.log(names);  // ['Alice', 'Bob', 'Charlie']

const arrays = [[1, 2], [3, 4], [5, 6]];
const flattened = arrays.map(pair => pair[0] + pair[1]);
console.log(flattened);  // [3, 7, 11]

const books = [
  { title: 'Book A', author: { firstName: 'John', lastName: 'Doe' }, pages: 150, price: 19.99, releaseYear: 2020 },
  { title: 'Book B', author: { firstName: 'Jane', lastName: 'Smith' }, pages: 450, price: 24.99, releaseYear: 2018 },
  { title: 'Book C', author: { firstName: 'Emily', lastName: 'Jones' }, pages: 700, price: 29.99, releaseYear: 2015 }
];
const transformedBooks = books.map(book => {
  // 复杂逻辑在这里
  let readable;
  if (book.pages < 300) {
    readable = 'Quick read';
  } else if (book.pages >= 300 && book.pages <= 600) {
    readable = 'Moderate read';
  } else {
    readable = 'Long read';
  }
  const fullName = `${book.author.firstName} ${book.author.lastName}`;
  const currentYear = new Date().getFullYear();
  const discountPrice = currentYear - book.releaseYear > 5 ? book.price * 0.9 : book.price;
// ...用于展开对象的属性（相当于写在这里）
  return {
    ...book,
    readable,
    author: { ...book.author, fullName },
    discountPrice: parseFloat(discountPrice.toFixed(2)) // ensures the price is formatted to 2 decimal places
  };
});
console.log(transformedBooks);

const books = [1, 2, 3]
for (const i of books) {
  console.log(i)
}
// 1
// 2
// 3

const books = { id: 1, pname: 2 }
for (const i in books) {
  console.log(`${i}:${books[i]}`)
}
// id: 1
// pname: 2

const books = [1, 2]
books.forEach((element) => {
  console.log(element)
})
// 1
// 2