Javascript小白经典题型(二)

function getInfo(member, year) {
  member.name = "Lydia";
  year = "1998";
}
const person = { name: "Sarah" };
const birthYear = "1997";
getInfo(person, birthYear);
console.log(person, birthYear);

function greeting() {
  throw "Hello world!";
}
function sayHi() {
  try {
    const data = greeting();
    console.log("It worked!", data);
  } catch (e) {
    console.log("Oh no an error!", e);
  }
}
sayHi();

function Car() {
  this.make = "Lamborghini";
  return { make: "Maserati" };
}
const myCar = new Car();
console.log(myCar.make);

(() => {
  let x = (y = 10);
})();

console.log(typeof x);
console.log(typeof y);

class Dog {
  constructor(name) {
    this.name = name;
  }
}
Dog.prototype.bark = function() {
  console.log(`Woof I am ${this.name}`);
};
const pet = new Dog("Mara");
pet.bark();
delete Dog.prototype.bark;
pet.bark();

const set = new Set([1, 1, 2, 3, 4]);
console.log(set);
A: [1, 1, 2, 3, 4]
B: [1, 2, 3, 4]
C: {1, 1, 2, 3, 4}
D: {1, 2, 3, 4}

// counter.js
let counter = 10;
export default counter;
// index.js
import myCounter from "./counter";
myCounter += 1;
console.log(myCounter);

const name = "Lydia";
age = 21;
console.log(delete name);
console.log(delete age);

const numbers = [1, 2, 3, 4, 5];
const [y] = numbers;
console.log(y);

const user = { name: "Lydia", age: 21 };
const admin = { admin: true, ...user };
console.log(admin);

const person = { name: "Lydia" };
Object.defineProperty(person, "age", { value: 21 });
console.log(person);
console.log(Object.keys(person));

const settings = {
  username: "lydiahallie",
  level: 19,
  health: 90
};
const data = JSON.stringify(settings, ["level", "health"]);
console.log(data);

let num = 10;
const increaseNumber = () => num++;
const increasePassedNumber = number => number++;
const num1 = increaseNumber();
const num2 = increasePassedNumber(num1);
console.log(num1);
console.log(num2);

const value = { number: 10 };
const multiply = (x = { ...value }) => {
  console.log(x.number *= 2);
};
multiply();
multiply();
multiply(value);
multiply(value);

[1, 2, 3, 4].reduce((x, y) => console.log(x, y));

class Dog {
  constructor(name) {
    this.name = name;
  }
};

class Labrador extends Dog {
  // 1 
  constructor(name, size) {
    this.size = size;
  }
  // 2
  constructor(name, size) {
    super(name);
    this.size = size;
  }
  // 3
  constructor(size) {
    super(name);
    this.size = size;
  }
  // 4 
  constructor(name, size) {
    this.name = name;
    this.size = size;
  }

};

// index.js
console.log('running index.js');
import { sum } from './sum.js';
console.log(sum(1, 2));

// sum.js
console.log('running sum.js');
export const sum = (a, b) => a + b;

console.log(Number(2) === Number(2))
console.log(Boolean(false) === Boolean(false))
console.log(Symbol('foo') === Symbol('foo'))

const name = "Lydia Hallie"
console.log(name.padStart(13))
console.log(name.padStart(2))

console.log("??" + "??");

function* startGame() {
  const answer = yield "Do you love JavaScript?";
  if (answer !== "Yes") {
    return "Oh wow... Guess we're gone here";
  }
  return "JavaScript loves you back ??";
}
const game = startGame();
console.log(/* 1 */); // Do you love JavaScript?
console.log(/* 2 */); // JavaScript loves you back ??

console.log(String.raw`Hello\nworld`);

async function getData() {
  return await Promise.resolve("I made it!");
}
const data = getData();
console.log(data);

function addToList(item, list) {
  return list.push(item);
}

const result = addToList("apple", ["banana"]);
console.log(result);

const box = { x: 10, y: 20 };
Object.freeze(box);
const shape = box;
shape.x = 100;
console.log(shape)

const { name: myName } = { name: "Lydia" };
console.log(name);

function sum(a, b) {
  return a + b;
}

const add = () => {
  const cache = {};
  return num => {
    if (num in cache) {
      return `From cache! ${cache[num]}`;
    } else {
      const result = num + 10;
      cache[num] = result;
      return `Calculated! ${result}`;
    }
  };
};

const addFunction = add();
console.log(addFunction(10));
console.log(addFunction(10));
console.log(addFunction(5 * 2));

const myLifeSummedUp = ["?", "??", "??", "??"]

for (let item in myLifeSummedUp) {
  console.log(item)
}

for (let item of myLifeSummedUp) {
  console.log(item)
}

const list = [1 + 2, 1 * 2, 1 / 2]
console.log(list)

function sayHi(name) {
  return `Hi there, ${name}`
}
console.log(sayHi())

var status = "??"

setTimeout(() => {
  const status = "??"

  const data = {
    status: "??",
    getStatus() {
      return this.status
    }
  }

  console.log(data.getStatus())
  console.log(data.getStatus.call(this))
}, 0)

const person = {
  name: "Lydia",
  age: 21
}

let city = person.city
city = "Amsterdam"

console.log(person)

function checkAge(age) {
  if (age < 18) {
    const message = "Sorry, you're too young."
  } else {
    const message = "Yay! You're old enough!"
  }

  return message
}

console.log(checkAge(21))

fetch('https://www.website.com/api/user/1')
  .then(res => res.json())
  .then(res => console.log(res))

function getName(name) {
  const hasName = //
}

console.log("I want pizza"[0])

function sum(num1, num2 = num1) {
  console.log(num1 + num2)
}

sum(10)

// module.js 
export default () => "Hello world"
export const name = "Lydia"

// index.js 
import * as data from "./module"

console.log(data)

class Person {
  constructor(name) {
    this.name = name
  }
}

const member = new Person("John")
console.log(typeof member)

let newList = [1, 2, 3].push(4)

console.log(newList.push(5))

function giveLydiaPizza() {
  return "Here is pizza!"
}

const giveLydiaChocolate = () => "Here's chocolate... now go hit the gym already."

console.log(giveLydiaPizza.prototype)
console.log(giveLydiaChocolate.prototype)

const person = {
  name: "Lydia",
  age: 21
}

for (const [x, y] of Object.entries(person)) {
  console.log(x, y)
}

function getItems(fruitList, ...args, favoriteFruit) {
  return [...fruitList, ...args, favoriteFruit]
}

getItems(["banana", "apple"], "pear", "orange")

function nums(a, b) {
  if
  (a > b)
  console.log('a is bigger')
  else 
  console.log('b is bigger')
  return 
  a + b
}

console.log(nums(4, 2))
console.log(nums(1, 2))

class Person {
  constructor() {
    this.name = "Lydia"
  }
}

Person = class AnotherPerson {
  constructor() {
    this.name = "Sarah"
  }
}

const member = new Person()
console.log(member.name)

const info = {
  [Symbol('a')]: 'b'
}

console.log(info)
console.log(Object.keys(info))

const getList = ([x, ...y]) => [x, y]
const getUser = user => { name: user.name, age: user.age }

const list = [1, 2, 3, 4]
const user = { name: "Lydia", age: 21 }

console.log(getList(list))
console.log(getUser(user))

const name = "Lydia"

console.log(name())

// ??? This is my 100th question! ???

const output = `${[] && 'Im'}possible!
You should${'' && `n't`} see a therapist after so much JavaScript lol`