JavaScript Output Based Questions

function show() {
  console.log(firstName);
  console.log(lastName);
  var firstName = "Ari";
  let lastName = "Khan";
}

show();

for (var i = 0; i < 3; i++) {
  setTimeout(() => console.log("var", i), 1);
}

for (let i = 0; i < 3; i++) {
  setTimeout(() => console.log("let", i), 1);
}

const ring = {
  r: 5,
  diameter() {
    return this.r * 2;
  },
  circumference: () => 2 * Math.PI * this.r,
};

console.log(ring.diameter());
console.log(ring.circumference());

+false;
!"hello";

const key = { size: "tiny" };
const item = { name: "mouse", tiny: true };

let obj1 = { msg: "Hi" };
let obj2;
obj2 = obj1;
obj1.msg = "Hey";
console.log(obj2.msg);

let a = 4;
let b = new Number(4);
let c = 4;

console.log(a == b);
console.log(a === b);
console.log(b === c);

class Gecko {
  static paint(newColor) {
    this.color = newColor;
    return this.color;
  }
}

const gary = new Gecko();
console.log(gary.paint("orange"));

"use strict";
let title;
titl = {}; // typo
console.log(titl);

function bark() {
  console.log("Woof!");
}

bark.kind = "dog";

function Person(first, last) {
  this.first = first;
  this.last = last;
}

const member = new Person("Ari", "Khan");
Person.fullName = function () {
  return this.first + " " + this.last;
};

console.log(member.fullName());

"use strict";
function Person(first, last) {
  this.first = first;
  this.last = last;
}

const ari = new Person("Ari", "Khan");
const sam = Person("Sam", "Lee");

console.log(ari);
console.log(sam);

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

sum(1, "2");

let n = 0;
console.log(n++);
console.log(++n);
console.log(n);

function info(a, b, c) {
  console.log(a);
  console.log(b);
  console.log(c);
}

const person = "Mia";
const age = 30;

info`${person} is ${age} years old`;

function checkAge(data) {
  if (data === { age: 18 }) {
    console.log("Adult");
  } else if (data == { age: 18 }) {
    console.log("Still adult");
  } else {
    console.log("No age");
  }
}

checkAge({ age: 18 });

function getAge(...args) {
  console.log(typeof args);
}

getAge(21);

function getAge() {
  "use strict";
  age = 21;
  console.log(age);
}

getAge();

const total = eval("10*10+5");

sessionStorage.setItem("token", "abc");

var num = 8;
var num = 10;
console.log(num);

const obj = { 1: "a", 2: "b" };
const set = new Set([1, 2, 3]);

obj.hasOwnProperty("1");
obj.hasOwnProperty(1);
set.has("1");
set.has(1);

const obj = { a: "one", b: "two", a: "three" };
console.log(obj);

for (let i = 1; i < 5; i++) {
  if (i === 3) continue;
  console.log(i);
}

String.prototype.sayPizza = () => "Pizza time!";
const name = "Noah";
console.log(name.sayPizza());

const a = {};
const b = { key: "b" };
const c = { key: "c" };

a[b] = 123;
a[c] = 456;

console.log(a[b]);

const first = () => console.log("First");
const second = () => setTimeout(() => console.log("Second"));
const third = () => console.log("Third");

second();
first();
third();

<div onclick="console.log('outer')">
  <div onclick="console.log('inner')">
    <button onclick="console.log('button')">Click</button>
  </div>
</div>

<div onclick="console.log('div')">
  <p onclick="console.log('p')">Tap</p>
</div>

const person = { name: "Noah" };

function sayHi(age) {
  return this.name + " is " + age;
}

console.log(sayHi.call(person, 21));
console.log(sayHi.bind(person, 21));

function sayHi() {
  return (() => 0)();
}

console.log(typeof sayHi());

0;
new Number(0);
("");
(" ");
new Boolean(false);
undefined;

console.log(typeof typeof 1);

const nums = [1, 2, 3];
nums[10] = 11;
console.log(nums);

(() => {
  let x, y;
  try {
    throw new Error("oops");
  } catch (x) {
    (x = 1), (y = 2);
    console.log(x);
  }
  console.log(x);
  console.log(y);
})();

[[0, 1], [2, 3]].reduce(
  (acc, cur) => acc.concat(cur),
  [1, 2]
);

!!null;
!!"";
!!1;

setInterval(() => console.log("Hi"), 1000);

[..."Maya"];

function* gen(i) {
  yield i;
  yield i * 2;
}

const g = gen(6);
console.log(g.next().value);
console.log(g.next().value);

const first = new Promise((res) => setTimeout(res, 400, "first"));
const second = new Promise((res) => setTimeout(res, 50, "second"));

Promise.race([first, second]).then((v) => console.log(v));

let person = { name: "Ari" };
const members = [person];
person = null;

console.log(members);

const person = { name: "Ari", age: 21 };

for (const key in person) {
  console.log(key);
}

console.log(3 + 4 + "5");

const value = parseInt("7*6", 10);

[1, 2, 3].map((n) => {
  if (typeof n === "number") return;
  return n * 2;
});

function update(person, year) {
  person.name = "Kai";
  year = "2000";
}

const person = { name: "Zoe" };
const birthYear = "1999";

update(person, birthYear);
console.log(person, birthYear);

function boom() {
  throw "Boom!";
}

function test() {
  try {
    boom();
    console.log("ok");
  } catch (e) {
    console.log("caught:", e);
  }
}

test();

function Car() {
  this.make = "Tesla";
  return { make: "Volvo" };
}

const car = new Car();
console.log(car.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 " + this.name);
};

const pet = new Dog("Rex");
pet.bark();

delete Dog.prototype.bark;
pet.bark();

const set = new Set([1, 1, 2, 3, 4]);
console.log(set);

// counter.js
let count = 10;
export default count;

// index.js
import counter from "./counter";
counter += 1;
console.log(counter);

var name = "Ari";
age = 21;

console.log(delete name);
console.log(delete age);

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

const user = { name: "Ari", age: 22 };
const admin = { admin: true, ...user };
console.log(admin);

const person = { name: "Ari" };
Object.defineProperty(person, "age", { value: 22 });

console.log(person);
console.log(Object.keys(person));

const settings = { user: "neo", level: 3, health: 90 };
const data = JSON.stringify(settings, ["level", "health"]);
console.log(data);

let num = 10;
const inc = () => num++;
const incCopy = (n) => n++;

const a = inc();
const b = incCopy(a);

console.log(a);
console.log(b);

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

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

console.log(Number(2) === Number(2));
console.log(Boolean(false) === Boolean(false));
console.log(Symbol("x") === Symbol("x"));

const name = "Nova";
console.log(name.padStart(6));
console.log(name.padStart(2));

console.log("foo" + "bar");

function* startGame() {
  const answer = yield "Do you like JS?";
  if (answer !== "Yes") return "Game over";
  return "You are awesome";
}

const game = startGame();
console.log(/* 1 */); // Do you like JS?
console.log(/* 2 */); // You are awesome

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

async function getData() {
  return await Promise.resolve("Done!");
}

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 { firstName: alias } = { firstName: "Ari" };
console.log(firstName);

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

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

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

const life = ["coffee", "code", "pizza"];

for (let i in life) console.log(i);
for (let v of life) console.log(v);

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

function sayHi(name) {
  return "Hi, " + name;
}

console.log(sayHi());

var mood = "cool";

setTimeout(function () {
  const mood = "warm";
  const data = {
    mood: "fresh",
    getMood() {
      return this.mood;
    },
  };

  console.log(data.getMood());
  console.log(data.getMood.call({ mood: "ok" }));
}, 0);

const person = { name: "Ari", age: 21 };
let city = person.city;
city = "Oslo";
console.log(person);

function checkAge(age) {
  if (age < 18) {
    const msg = "Too young";
  } else {
    const msg = "Old enough";
  }
  return msg;
}

console.log(checkAge(21));

fetch("https://example.com/api/user/1")
  .then((res) => res.json())
  .then((data) => console.log(data));

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

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

function sum(a, b = a) {
  console.log(a + b);
}

sum(10);

// module.js
export default () => "Hello";
export const name = "Ari";

// 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 list = [1, 2, 3].push(4);
console.log(list.push(5));

function givePizza() {
  return "Pizza!";
}
const giveChoco = () => "Chocolate!";

console.log(givePizza.prototype);
console.log(giveChoco.prototype);

const person = { name: "Ari", age: 21 };
for (const [k, v] of Object.entries(person)) {
  console.log(k, v);
}

function getItems(list, ...rest, last) {
  return [...list, ...rest, last];
}

getItems(["a", "b"], "c", "d");

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

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

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

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

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

const info = { [Symbol("x")]: "y" };
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: "Ari", age: 21 };

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

const name = "Ari";
console.log(name());

const output = `${[] && "Not"}possible!
You should${"" && "n't"} worry`;

const one = false || {} || null;
const two = null || false || "";
const three = [] || 0 || true;

console.log(one, two, three);

const wait = () => new Promise((res) => setTimeout(() => res("done"), 0));

function first() {
  wait().then((v) => console.log("first:", v));
  console.log("first: sync");
}

async function second() {
  console.log("second:", await wait());
  console.log("second: sync");
}

first();
second();

const set = new Set();
set.add(1);
set.add("Ari");
set.add({ name: "Ari" });

for (let item of set) {
  console.log(item + 2);
}

Promise.resolve(5);

function compare(a, b = person) {
  if (a !== b) console.log("Different");
  else console.log("Same");
}

const person = { name: "Ari" };
compare(person);

const config = {
  red: true,
  blue: false,
  green: true,
};

const colors = ["pink", "red", "blue"];

console.log(config.colors?.[1]);

console.log("hi" === "hi");

const items = ["spark", "leaf", "smile"];

items.map((x) => x + "x");
items.filter((x) => x !== "leaf");
items.find((x) => x !== "leaf");
items.reduce((acc, cur) => acc + "x", "");
items.slice(1, 2, "x");
items.splice(1, 2, "x");

const menu = ["pizza", "chocolate", "avocado", "burger"];
const info = { favorite: menu[0] };

info.favorite = "pasta";

console.log(menu);

let name = "Nora";

function getName() {
  console.log(name);
  let name = "Sasha";
}

getName();

function* genOne() {
  yield ["a", "b", "c"];
}

function* genTwo() {
  yield* ["a", "b", "c"];
}

const one = genOne();
const two = genTwo();

console.log(one.next().value);
console.log(two.next().value);

console.log(`${(x => x)("I enjoy")} to code`);

let config = {
  timer: setInterval(() => {
    console.log("Tick");
  }, 1000),
};

config = null;

const myMap = new Map();
const myFunc = () => "greeting";

myMap.set(myFunc, "Hello world!");

// 1
myMap.get("greeting");
// 2
myMap.get(myFunc);
// 3
myMap.get(() => "greeting");

const person = { name: "Nora", age: 20 };

const changeAge = (x = { ...person }) => (x.age += 1);
const changeAgeAndName = (x = { ...person }) => {
  x.age += 1;
  x.name = "Sara";
};

changeAge(person);
changeAgeAndName();

console.log(person);

function sumValues(x, y, z) {
  return x + y + z;
}

let num = 1;
const list = ["party", "hat", "smile", "wild"];

console.log(list[(num += 1)]);

const person = {
  firstName: "Nora",
  lastName: "Hill",
  pet: {
    name: "Milo",
    breed: "Hound",
  },
  getFullName() {
    return `${this.firstName} ${this.lastName}`;
  },
};

console.log(person.pet?.name);
console.log(person.pet?.family?.name);
console.log(person.getFullName?.());
console.log(member.getLastName?.());

const groceries = ["banana", "apple", "peanuts"];

if (groceries.indexOf("banana")) {
  console.log("We should buy bananas");
} else {
  console.log("No bananas needed");
}

const config = {
  languages: [],
  set language(lang) {
    return this.languages.push(lang);
  },
};

console.log(config.language);

const name = "Nora Hill";

console.log(!typeof name === "object");
console.log(!typeof name === "string");

const add = x => y => z => {
  console.log(x, y, z);
  return x + y + z;
};

add(4)(5)(6);

async function* range(start, end) {
  for (let i = start; i <= end; i++) {
    yield Promise.resolve(i);
  }
}

(async () => {
  const gen = range(1, 3);
  for await (const item of gen) {
    console.log(item);
  }
})();

const myFunc = ({ x, y, z }) => {
  console.log(x, y, z);
};

myFunc(1, 2, 3);

function getFine(speed, amount) {
  const formattedSpeed = new Intl.NumberFormat("en-US", {
    style: "unit",
    unit: "mile-per-hour",
  }).format(speed);

  const formattedAmount = new Intl.NumberFormat("en-US", {
    style: "currency",
    currency: "USD",
  }).format(amount);

  return `The driver drove ${formattedSpeed} and has to pay ${formattedAmount}`;
}

console.log(getFine(130, 300));

const spooky = ["ghost", "pumpkin", "web"];
({ item: spooky[3] } = { item: "skull" });

console.log(spooky);

const name = "Nora Hill";
const age = 21;

console.log(Number.isNaN(name));
console.log(Number.isNaN(age));

console.log(isNaN(name));
console.log(isNaN(age));

const randomValue = 21;

function getInfo() {
  console.log(typeof randomValue);
  const randomValue = "Nora Hill";
}

getInfo();

const myPromise = Promise.resolve("Great data");

(async () => {
  try {
    console.log(await myPromise);
  } catch {
    throw new Error("Oops");
  } finally {
    console.log("Finally!");
  }
})();

const items = ["a", ["b", "b", ["c", "c"]]];

console.log(items.flat(1));

class Counter {
  constructor() {
    this.count = 0;
  }
  increment() {
    this.count++;
  }
}

const counterOne = new Counter();
counterOne.increment();
counterOne.increment();

const counterTwo = counterOne;
counterTwo.increment();

console.log(counterOne.count);

const myPromise = Promise.resolve(Promise.resolve("Promise"));

function funcOne() {
  setTimeout(() => console.log("Timeout 1"), 0);
  myPromise.then((res) => res).then((res) => console.log(res + " 1"));
  console.log("Last line 1");
}

async function funcTwo() {
  const res = await myPromise;
  console.log(res + " 2");
  setTimeout(() => console.log("Timeout 2"), 0);
  console.log("Last line 2");
}

funcOne();
funcTwo();

// sum.js
export default function sum(x) {
  return x + x;
}

// index.js
import * as sum from "./sum";

const handler = {
  set: () => console.log("Added a new property!"),
  get: () => console.log("Accessed a property!"),
};

const person = new Proxy({}, handler);

person.name = "Nora";
person.name;

const person = { name: "Nora Hill" };

Object.seal(person);

const person = {
  name: "Nora Hill",
  address: {
    street: "100 Main St",
  },
};

Object.freeze(person);

const add = (x) => x + x;

function myFunc(num = 2, value = add(num)) {
  console.log(num, value);
}

myFunc();
myFunc(3);

class Counter {
  #number = 10;

  increment() {
    this.#number++;
  }

  getNum() {
    return this.#number;
  }
}

const counter = new Counter();
counter.increment();

console.log(counter.#number);

const teams = [
  { name: "Team 1", members: ["Paul", "Lisa"] },
  { name: "Team 2", members: ["Laura", "Tim"] },
];

function* getMembers(members) {
  for (let i = 0; i < members.length; i++) {
    yield members[i];
  }
}

function* getTeams(teams) {
  for (let i = 0; i < teams.length; i++) {
    // missing
  }
}

const obj = getTeams(teams);
obj.next();
obj.next();

const person = {
  name: "Nora Hill",
  hobbies: ["coding"],
};

function addHobby(hobby, hobbies = person.hobbies) {
  hobbies.push(hobby);
  return hobbies;
}

addHobby("running", []);
addHobby("dancing");
addHobby("baking", person.hobbies);

console.log(person.hobbies);

class Bird {
  constructor() {
    console.log("I'm a bird.");
  }
}

class Flamingo extends Bird {
  constructor() {
    console.log("I'm pink.");
    super();
  }
}

const pet = new Flamingo();

const items = ["tree", "santa", "gift", "star"];

/* 1 */ items.push("reindeer");
/* 2 */ items.splice(0, 2);
/* 3 */ items = [...items, "toast"];
/* 4 */ items.length = 0;

const person = {
  name: "Nora Hill",
  age: 21,
};

[...person];

let count = 0;
const nums = [0, 1, 2, 3];

nums.forEach((num) => {
  if (num) count += 1;
});

console.log(count);

function getFruit(fruits) {
  console.log(fruits?.[1]?.[1]);
}

getFruit([["orange", "banana"], ["pineapple"]]);
getFruit();
getFruit([["pineapple"], ["orange", "banana"]]);

class Calc {
  constructor() {
    this.count = 0;
  }
  increase() {
    this.count++;
  }
}

const calc = new Calc();
new Calc().increase();

console.log(calc.count);

const user = {
  email: "e@mail.com",
  password: "12345",
};

const updateUser = ({ email, password }) => {
  if (email) {
    Object.assign(user, { email });
  }
  if (password) {
    user.password = password;
  }
  return user;
};

const updatedUser = updateUser({ email: "new@mail.com" });

console.log(updatedUser === user);

const fruit = ["banana", "orange", "apple"];

fruit.slice(0, 1);
fruit.splice(0, 1);
fruit.unshift("grape");

console.log(fruit);

const animals = {};
let dog = { emoji: "dog" };
let cat = { emoji: "cat" };

animals[dog] = { ...dog, name: "Mara" };
animals[cat] = { ...cat, name: "Sara" };

console.log(animals[dog]);

const user = {
  email: "my@mail.com",
  updateEmail: (email) => {
    this.email = email;
  },
};

user.updateEmail("new@mail.com");
console.log(user.email);

const p1 = Promise.resolve("First");
const p2 = Promise.resolve("Second");
const p3 = Promise.reject("Third");
const p4 = Promise.resolve("Fourth");

const runPromises = async () => {
  const res1 = await Promise.all([p1, p2]);
  const res2 = await Promise.all([p3, p4]);
  return [res1, res2];
};

runPromises()
  .then((res) => console.log(res))
  .catch((err) => console.log(err));

const keys = ["name", "age"];
const values = ["Nora", 22];

const method = /* ?? */;
Object[method](keys.map((_, i) => [keys[i], values[i]]));

const createMember = ({ email, address = {} }) => {
  const valid = /.+@.+..+/.test(email);
  if (!valid) throw new Error("Valid email pls");
  return {
    email,
    address: address ? address : null,
  };
};

const member = createMember({ email: "my@mail.com" });
console.log(member);

let randomValue = { name: "Nora" };
randomValue = 23;

if (!typeof randomValue === "string") {
  console.log("It's not a string!");
} else {
  console.log("Yay it's a string!");
}