mutableAPI.js

//添加和删除元素API
const stack = ["A", "B"];
// console.log(stack.pop())
console.log(stack.push("C","D","e"));
console.log(stack);

const queue = ["B", "C"];
// console.log(queue.unshift("A","B","C"));
console.log(queue.shift());
console.log(queue);

const numbers = [1, 2, 5];
console.log(numbers.splice(0, 3, 7, 8, 9));


const nums = [1, 10, 2, 5];

// 错误做法：
nums.sort(); 
console.log(nums)
// 正确做法：
// nums.sort((a, b) => a - b); // 升序：[1, 2, 5, 10]
nums.sort((a, b) => b - a);
console.log(nums)
nums.reverse();
console.log(nums)

const fruits = ["banana", "apple", "cherry"];
fruits.sort(); 
console.log(fruits); // ["apple", "banana", "cherry"]

const words = ["河", "波", "多"];
// 使用 localeCompare，按拼音/字母顺序排
words.sort((a, b) => a.localeCompare(b)); 

console.log(words); // ["波", "多", "河"] (B -> D -> H)

const files = ["v1.js", "v10.js", "v2.js"];

// 错误排序：["v1.js", "v10.js", "v2.js"]
files.sort();
console.log(files)
// 聪明排序：["v1.js", "v2.js", "v10.js"]
files.sort((a, b) => a.localeCompare(b, undefined, { numeric: true }));
console.log(files)

//r如何自定义排序，比如对国际音标的高低
const wubiMap = { "河": "iskg", "波": "ihcy", "多": "qqkk" };

const queque2 = ["河", "波", "多"];
words.sort((a, b) => wubiMap[a].localeCompare(wubiMap[b]));
console.log(queque2);

// 声明函数
// 传统函数声明
function greet(username) {
    return `Hello,${username}!`
//   return "你好，" + username + "！";
}

// 调用函数
let message = greet("小明");
console.log(message); // 输出: 你好，小明！

//箭头函数
//  const hello = (username) => {
//     return `Hello,${username}!`
//  }
//  console.log(hello("xiaomao"))
//简写版本
const hello = (a) => `hello,${a}!`;
console.log(hello("xiaomao"));

//对象与数组之间的转换
const myObj = {
    "100": "我是100",
    "name": "负里",
    "1": "我是1",
    "age": 23,
    "0": "我是0"
};

console.log(Object.keys(myObj));
console.log(Object.values(myObj));

//数组和对象的转换练习
//练习1
const fitnessData = {
    Monday: 250,
    Tuesday: 450,
    Wednesday: 320,
    Thursday: 150,
    Friday: 500
};

//解构法
const fit = Object.entries(fitnessData);
const highFit = fit.filter(([day, calorie]) => calorie > 300); // 直接拿值比对
const nameOnly = highFit.map(([day]) => day); // 只要第一个零件


// console.log(fit);
// const highFit = fit.filter(item => {
//     //item是 ['Monday', 250]
//     //item[o]是key Monday
//     //item[1]是value 250
//     return item[1] > 300;
// })
// console.log(highFit);
// const nameOnly = highFit.map(item => {
//     return item[0];
// });
// console.log(nameOnly);



//练习2
const researchData = [
    ["河", 120],
    ["波", 150],
    ["多", 90]
];

const obData = Object.fromEntries(researchData);
console.log(obData);
const directData = {...obData};
console.log(directData);
//这两个输出结果是一样的？？？

//练习3
const liqiSnacks = {
    "冻干": 60,
    "罐头": 15,
    "小鱼干": 10
};

// const newSnacks = Object.entries(liqiSnacks);
// console.log(newSnacks);
// const zhangJia = newSnacks.map(item => {
//    item[1] += 5
//    return item;
// });
// console.log(zhangJia);
// const finalSnacks = Object.fromEntries(zhangJia);
// console.log(finalSnacks);


const finalSnacks = Object.fromEntries(Object.entries(liqiSnacks).map(([name, price]) => [name, price +5]));
console.log(finalSnacks);

//拆开对象
const wordInfo = { word: "河", duration: 120, location: "苏州", change: true };
const { word, change } = wordInfo;
console.log(`${word}是例字，发生了${change}变化`)