چیت‌شیت JavaScript

1const sum = 8 + 3;2const difference = 8 - 3;3const product = 8 * 3;4const quotient = 8 / 3;5const remainder = 8 % 3;

1console.log(5 === "5"); // false2console.log(5 !== 3); // true3console.log(10 >= 10); // true

1const canSubmit = isReady && score >= 10;2const displayName = nickname || "مهمان";3const isUnavailable = !isReady;

1const retryLimit = configuredLimit ?? 3;2const label = customLabel ?? "بدون عنوان";3console.log(0 ?? 5); // 0

1if (score >= 18) {2  console.log("عالی");3} else if (score >= 10) {4  console.log("قبول");5} else {6  console.log("نیازمند تمرین");7}

1const status = isReady ? "آماده" : "در انتظار";

1switch (status) {2  case "ready":3    console.log("شروع");4    break;5  case "waiting":6    console.log("کمی صبر کنید");7    break;8  default:9    console.log("وضعیت نامشخص");10}

1for (let index = 0; index < 3; index += 1) {2  console.log(index);3}

1let remaining = 3;2while (remaining > 0) {3  console.log(remaining);4  remaining -= 1;5}

1const colors = ["آبی", "سبز"];2for (const color of colors) {3  console.log(color);4}

1const settings = { theme: "dark", compact: true };2for (const key in settings) {3  console.log(key, settings[key]);4}

1for (const value of [1, 2, 3, 4]) {2  if (value === 2) continue;3  if (value === 4) break;4  console.log(value);5}

1function add(first, second) {2  return first + second;3}45console.log(add(4, 6)); // 10

1function greet(name = "دوست") {2  return "سلام " + name;3}45console.log(greet());

1const multiply = (first, second) => first * second;2const double = value => value * 2;

1function sumAll(...values) {2  return values.reduce((total, value) => total + value, 0);3}45console.log(sumAll(2, 3, 4)); // 9

1if (true) {2  const message = "داخل بلوک";3  console.log(message);4}5// message بیرون از بلوک در دسترس نیست.

1function runWith(value, callback) {2  return callback(value);3}45const result = runWith(5, number => number * 2);

1const scores = [12, 16, 19];2console.log(scores[0]); // 123console.log(scores.length); // 3

1const queue = ["الف"];2queue.push("ب");3const lastItem = queue.pop();

1const items = ["میانی"];2items.unshift("اول");3const firstItem = items.shift();

1const prices = [10, 20, 30];2const discounted = prices.map(price => price * 0.9);

1const scores = [8, 14, 19, 20];2const passing = scores.filter(score => score >= 10);3const firstHighScore = scores.find(score => score > 18);

1const amounts = [3, 5, 7];2const total = amounts.reduce(3  (sum, amount) => sum + amount,4  05);

1const first = [1, 2];2const second = [3, 4];3const combined = [...first, ...second];

1["چای", "قهوه"].forEach((drink, index) => {2  console.log(index, drink);3});

1const user = { name: "Mina", score: 18 };2console.log(user.name);3console.log(user["score"]);

1const field = "email";2const email = "mina@example.com";3const profile = { email, [field + "Verified"]: true };

1const user = { name: "Mina", role: "editor" };2const { name, role, active = true } = user;

1const defaults = { theme: "light", compact: false };2const preferences = { ...defaults, theme: "dark" };

1const counter = {2  value: 0,3  increment() {4    this.value += 1;5  },6};78counter.increment();

1class Animal {2  constructor(name) {3    this.name = name;4  }56  speak() {7    return this.name + " makes a sound";8  }9}1011const pet = new Animal("Milo");

1class Dog extends Animal {2  speak() {3    return super.speak() + "!";4  }5}

1// math.js2export const add = (a, b) => a + b;3export const subtract = (a, b) => a - b;45// app.js6import { add, subtract } from "./math.js";

1// formatter.js2export default function formatName(name) {3  return name.trim();4}56// app.js7import formatName from "./formatter.js";

1export { add, subtract } from "./math.js";2export { default as formatName } from "./formatter.js";

1const task = new Promise((resolve, reject) => {2  const succeeded = true;3  if (succeeded) resolve("انجام شد");4  else reject(new Error("عملیات ناموفق بود"));5});

1task2  .then(result => {3    console.log(result);4    return result.length;5  })6  .then(length => console.log(length))7  .catch(error => console.error(error));

1async function loadMessage() {2  try {3    const message = await task;4    console.log(message);5  } catch (error) {6    console.error(error);7  }8}

1const [profile, courses] = await Promise.all([2  loadProfile(),3  loadCourses(),4]);

1const results = await Promise.allSettled([2  loadProfile(),3  loadCourses(),4]);

1const account = await loadAccount();2const settings = await loadSettings(account.id);

1const payload = { title: "درس", complete: false };2const json = JSON.stringify(payload);3const restored = JSON.parse(json);

1const button = document.querySelector("#save");2button?.addEventListener("click", event => {3  console.log("ذخیره شد", event.currentTarget);4});

1async function loadItems() {2  const response = await fetch("/api/items");3  if (!response.ok) {4    throw new Error("دریافت داده ناموفق بود");5  }6  return response.json();7}

1const response = await fetch("/api/items", {2  method: "POST",3  headers: { "Content-Type": "application/json" },4  body: JSON.stringify({ title: "درس تازه" }),5});67if (!response.ok) {8  throw new Error("ثبت داده ناموفق بود");9}

1const request = new XMLHttpRequest();2request.open("GET", "/api/items");3request.responseType = "json";4request.addEventListener("load", () => {5  if (request.status >= 200 && request.status < 300) {6    console.log(request.response);7  }8});9request.send();

1const settings = { theme: "dark" };2settings.theme = "light"; // مجاز است34let count = 1;5count += 1;67if (count > 1) {8  const message = "در محدودهٔ بلوک";9}

1const name = "Nina";2const greeting = `سلام، ${name}!`;3const message = `این رشته4چند خط دارد.`;

1const coordinates = [12, 24, 36];2const [x, y] = coordinates;3const [first, , third] = coordinates;4const [head, ...rest] = coordinates;

1const user = { id: 7, profile: { name: "Nina" } };2const {3  id: userId,4  role = "reader",5  profile: { name },6} = user;

1function greet({ name = "دوست", greeting = "سلام" } = {}) {2  return `${greeting}، ${name}!`;3}45greet({ name: "Nina" });

1function sum(first = 0, ...values) {2  return values.reduce((total, value) => total + value, first);3}45sum(1, 2, 3); // 6

1const admins = ["Ava"];2const editors = ["Nima", "Sara"];3const users = [...admins, ...editors];45const copied = [...users];

1const defaults = { theme: "light", compact: false };2const options = {3  ...defaults,4  ...userOptions,5  compact: true,6};

1function logAll(label, ...values) {2  console.log(label, ...values);3}45const scores = [18, 20];6logAll("نمره‌ها:", ...scores);

1const field = "email";2const email = "nina@example.com";3const profile = {4  email,5  [`${field}Verified`]: true,6};

1const account = {2  _closed: false,3  get closed() { return this._closed; },4  set closed(value) { this._closed = Boolean(value); },5  close() { this.closed = true; },6};

1const double = value => value * 2;2const add = (first, second) => first + second;3const makeUser = name => ({ name, active: true });

1class Circle {2  constructor(radius) {3    this.radius = radius;4  }56  getArea() {7    return Math.PI * this.radius ** 2;8  }9}

1class ColoredCircle extends Circle {2  constructor(radius, color) {3    super(radius);4    this.color = color;5  }6}

1class Token {2  static #prefix = "id";3  #value;45  constructor(value) {6    this.#value = value;7  }89  static create(value) {10    return new Token(`${Token.#prefix}-${value}`);11  }12}

1const tasks = [loadProfile(), loadCourses()];23const results = await Promise.allSettled(tasks);4const first = await Promise.race(tasks);5const safeValue = await Promise.resolve("آماده");

1// math.js2export const add = (a, b) => a + b;3export default function multiply(a, b) {4  return a * b;5}

1import multiply, { add as sum } from "./math.js";23console.log(sum(2, 3));4console.log(multiply(2, 3));

1const { openDialog } = await import("./dialog.js");2openDialog();34console.log(import.meta.url);

1function* sequence() {2  yield 1;3  yield 2;4  return 3;5}67const iterator = sequence();8iterator.next(); // { value: 1, done: false }

1const range = {2  *[Symbol.iterator]() {3    yield 1;4    yield 2;5    yield 3;6  },7};89for (const value of range) console.log(value);

1const code = "7".padStart(3, "0");2const label = "ES6".padEnd(6, ".");34Number.isInteger(4); // true5Number.isNaN(Number("x")); // true

1const distance = Math.hypot(3, 4);2const nodes = Array.from(3  document.querySelectorAll("button"),4);56const hasTopic = ["css", "js"].includes("js");

1const square = 5 ** 2;2const hasNaN = [NaN].includes(NaN);34console.log(square, hasNaN);