JavaScript

async function processData() {
  const promise1 = Promise.resolve('first');
  const promise2 = Promise.reject('error');
  const promise3 = Promise.resolve('third');
  
  try {
    const result = await Promise.allSettled([promise1, promise2, promise3]);
    console.log(result[0].status);
    console.log(result[1].reason);
    console.log(result[2].value);
  } catch (error) {
    console.log('caught:', error);
  }
}

processData();

const data = [
  { type: 'income', amount: 1000, category: 'salary' },
  { type: 'expense', amount: 200, category: 'food' },
  { type: 'income', amount: 500, category: 'freelance' },
  { type: 'expense', amount: 150, category: 'transport' }
];

const result = data.reduce((acc, item) => {
  const key = item.type;
  acc[key] = (acc[key] || 0) + item.amount;
  return acc;
}, {});

console.log(result.income - result.expense);

console.log(typeof myVar);
console.log(typeof myFunc);
console.log(typeof myArrow);

var myVar = 'initialized';

function myFunc() {
  return 'function declaration';
}

var myArrow = () => 'arrow function';

console.log(typeof myVar);
console.log(typeof myFunc);
console.log(typeof myArrow);

const config = { api: 'v1', timeout: 5000 };
Object.seal(config);

const settings = { theme: 'dark', lang: 'en' };
Object.freeze(settings);

config.api = 'v2';
config.retries = 3;
settings.theme = 'light';
settings.debug = true;

console.log(config.api);
console.log(config.retries);
console.log(settings.theme);
console.log(settings.debug);

const obj = { a: 1, b: 2, c: 3 };
const entries = Object.entries(obj);
const keys = Object.keys(obj);
const values = Object.values(obj);

const result = {
  entriesLength: entries.length,
  keysJoined: keys.join('-'),
  valuesSum: values.reduce((sum, val) => sum + val, 0),
  firstEntry: entries[0]
};

console.log(result.entriesLength);
console.log(result.keysJoined);
console.log(result.valuesSum);
console.log(result.firstEntry);

function* outer() {
  yield 1;
  yield* inner();
  yield 4;
}

function* inner() {
  yield 2;
  yield 3;
}

const gen = outer();
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next().value);
console.log(gen.next().value);

const user = {
  name: 'Sarah',
  age: 28,
  getName() {
    return this.name;
  }
};

const { getName } = user;
const boundGetName = user.getName.bind(user);

console.log(getName());
console.log(boundGetName());
console.log(user.getName());

function* fibonacci() {
  let a = 0, b = 1;
  yield a;
  yield b;
  while (true) {
    let next = a + b;
    yield next;
    a = b;
    b = next;
  }
}

const gen = fibonacci();
const results = [];
for (let i = 0; i < 6; i++) {
  results.push(gen.next().value);
}
console.log(results.join(','));