List of (Advanced) JavaScript Questions

function sayHi() {
  console.log(name);
  console.log(age);
  var name = "Lydia";
  let age = 21;
}

sayHi();

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

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

const shape = {
  radius: 10,
  diameter() {
    return this.radius * 2;
  },
  perimeter: () => 2 * Math.PI * this.radius
};

console.log(shape.diameter());
console.log(shape.perimeter());

+true;
!"Lydia";

const bird = {
  size: "small"
};

const mouse = {
  name: "Mickey",
  small: true
};

let c = { greeting: "Hey!" };
let d;

d = c;
c.greeting = "Hello";
console.log(d.greeting);

let a = 3;
let b = new Number(3);
let c = 3;

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

class Chameleon {
  static colorChange(newColor) {
    this.newColor = newColor;
    return this.newColor;
  }

  constructor({ newColor = "green" } = {}) {
    this.newColor = newColor;
  }
}

const freddie = new Chameleon({ newColor: "purple" });
console.log(freddie.colorChange("orange"));

let greeting;
greetign = {}; // Typo!
console.log(greetign);

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

bark.animal = "dog";

function Person(firstName, lastName) {
  this.firstName = firstName;
  this.lastName = lastName;
}

const member = new Person("Lydia", "Hallie");
Person.getFullName = function() {
  return `${this.firstName} ${this.lastName}`;
};

console.log(member.getFullName());

function Person(firstName, lastName) {
  this.firstName = firstName;
  this.lastName = lastName;
}

const lydia = new Person("Lydia", "Hallie");
const sarah = Person("Sarah", "Smith");

console.log(lydia);
console.log(sarah);

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

sum(1, "2");

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

function getPersonInfo(one, two, three) {
  console.log(one);
  console.log(two);
  console.log(three);
}

const person = "Lydia";
const age = 21;

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

function checkAge(data) {
  if (data === { age: 18 }) {
    console.log("You are an adult!");
  } else if (data == { age: 18 }) {
    console.log("You are still an adult.");
  } else {
    console.log(`Hmm.. You don't have an age I guess`);
  }
}

checkAge({ age: 18 });

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

getAge(21);

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

getAge();

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

sessionStorage.setItem("cool_secret", 123);

var num = 8;
var num = 10;

console.log(num);

const obj = { 1: "a", 2: "b", 3: "c" };
const set = new Set([1, 2, 3, 4, 5]);

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.giveLydiaPizza = () => {
  return "Just give Lydia pizza already!";
};

const name = "Lydia";

name.giveLydiaPizza();

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

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

console.log(a[b]);

const foo = () => console.log("First");
const bar = () => setTimeout(() => console.log("Second"));
const baz = () => console.log("Third");

bar();
foo();
baz();

const person = { name: "Lydia" };

function sayHi(age) {
  console.log(`${this.name} is ${age}`);
}

sayHi.call(person, 21);
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 numbers = [1, 2, 3];
numbers[10] = 11;
console.log(numbers);

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

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

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

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

[..."Lydia"];

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

const gen = generator(10);

console.log(gen.next().value);
console.log(gen.next().value);

const firstPromise = new Promise((res, rej) => {
  setTimeout(res, 500, "one");
});

const secondPromise = new Promise((res, rej) => {
  setTimeout(res, 100, "two");
});

Promise.race([firstPromise, secondPromise]).then(res => console.log(res));

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

console.log(members);

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

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

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

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

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

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);

// 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))