JavaScript

CHALLENGE

const curry = (fn) => {
  const arity = fn.length;
  return function curried(...args) {
    if (args.length >= arity) {
      return fn(...args);
    }
    return (...moreArgs) => curried(...args, ...moreArgs);
  };
};

const volume = (l, w, h) => l * w * h;
const curriedVolume = curry(volume);

const withLength5 = curriedVolume(5);
const withLength5Width3 = withLength5(3);

console.log(typeof withLength5);
console.log(typeof withLength5Width3);
console.log(withLength5Width3(2));
console.log(curriedVolume(5)(3)(2) === withLength5(3)(2));

CHALLENGE

console.log('start');

setTimeout(() => console.log('timeout 1'), 0);

Promise.resolve()
  .then(() => {
    console.log('promise 1');
    setTimeout(() => console.log('timeout 2'), 0);
  })
  .then(() => console.log('promise 2'));

setTimeout(() => console.log('timeout 3'), 0);

queueMicrotask(() => console.log('microtask'));

console.log('end');

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CHALLENGE

class Pipeline {
  #value;
  #steps = [];

  constructor(value) {
    this.#value = value;
  }

  map(fn) {
    this.#steps.push({ type: 'map', fn });
    return this;
  }

  filter(fn) {
    this.#steps.push({ type: 'filter', fn });
    return this;
  }

  execute() {
    return this.#steps.reduce((acc, step) => {
      if (step.type === 'map') return acc.map(step.fn);
      if (step.type === 'filter') return acc.filter(step.fn);
      return acc;
    }, this.#value);
  }
}

const result = new Pipeline([1, 2, 3, 4, 5, 6])
  .filter(x => x % 2 === 0)
  .map(x => x ** 2)
  .filter(x => x > 10)
  .map(x => x - 1)
  .execute();

console.log(result);

🤟 Node.js 26.4 Adds Package Maps A minor release whose headline feature is the (experimental) implementation of package maps (which let Node resolve packages from a static JSON file rather than walking node_modules). Matteo Collina’s node:vfs subsystem also begins to make an appearance. Antoine du Hamel

CHALLENGE

function riskyOperation(value) {
  try {
    if (value === null) throw new TypeError("Null value");
    if (value < 0) throw new RangeError("Negative value");
    return value * 2;
  } catch (e) {
    if (e instanceof TypeError) {
      console.log(`TypeError: ${e.message}`);
      return -1;
    }
    console.log(`RangeError: ${e.message}`);
    return -2;
  } finally {
    console.log(`Finally: processed ${value}`);
  }
}

const results = [riskyOperation(5), riskyOperation(null), riskyOperation(-3)];
console.log(results);

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CHALLENGE

const compose = (...fns) => x => fns.reduceRight((acc, fn) => fn(acc), x);
const pipe = (...fns) => x => fns.reduce((acc, fn) => fn(acc), x);

const double = x => x * 2;
const addTen = x => x + 10;
const square = x => x ** 2;
const negate = x => -x;

const transform1 = compose(negate, square, addTen, double);
const transform2 = pipe(negate, square, addTen, double);

console.log(transform1(3));
console.log(transform2(3));

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CHALLENGE

const setA = new Set([1, 2, 3, 4, 5]);
const setB = new Set([3, 4, 5, 6, 7]);

const union = new Set([...setA, ...setB]);

const intersection = new Set([...setA].filter(x => setB.has(x)));

const differenceAB = new Set([...setA].filter(x => !setB.has(x)));

const symmetricDiff = new Set(
  [...setA, ...setB].filter(x => !(setA.has(x) && setB.has(x)))
);

console.log([...union].join(','));
console.log([...intersection].join(','));
console.log([...differenceAB].join(','));
console.log([...symmetricDiff].join(','));

CHALLENGE

const compose = (...fns) => x => fns.reduceRight((acc, fn) => fn(acc), x);
const pipe = (...fns) => x => fns.reduce((acc, fn) => fn(acc), x);

const double = x => x * 2;
const addTen = x => x + 10;
const square = x => x * x;
const negate = x => -x;

const transform1 = compose(negate, square, addTen, double);
const transform2 = pipe(negate, square, addTen, double);

console.log(transform1(3));
console.log(transform2(3));

CHALLENGE

async function fetchData(id) {
  if (id <= 0) throw new Error("Invalid ID");
  return { id, value: id * 10 };
}

async function process() {
  const results = await Promise.allSettled([
    fetchData(1),
    fetchData(-1),
    fetchData(3),
  ]);

  results.forEach(({ status, value, reason }) => {
    if (status === "fulfilled") {
      console.log(`✅ ${value.id}: ${value.value}`);
    } else {
      console.log(`❌ ${reason.message}`);
    }
  });
}

process();

CHALLENGE

const inventory = {
  warehouse: {
    shelves: [
      { id: 'A1', items: ['bolts', 'nuts', 'washers'] },
      { id: 'B2', items: ['hammers', 'wrenches'] },
    ],
    manager: { name: 'Carlos', shift: 'night' },
  },
};

const {
  warehouse: {
    shelves: [{ items: [firstItem, , thirdItem] }, { id: shelfId }],
    manager: { name, shift = 'day' },
  },
} = inventory;

console.log(`${name} | ${shift} | ${shelfId} | ${firstItem} | ${thirdItem}`);