function makeFns() {
  const result = [];
  for (var i = 0; i < 3; i++) {
    let j = i;
    result.push(() => i + j);
  }
  return result;
}
const fns = makeFns();
console.log(fns.map(f => f()).join(','));

class Base {}
class Derived extends Base {
  static [Symbol.hasInstance](instance) {
    return false;
  }
}
const d = new Derived();
console.log(d instanceof Derived, d instanceof Base, Object.getPrototypeOf(Derived) === Base);

function* inner() {
  yield 1;
  yield 2;
  return 'inner-done';
}

function* outer() {
  const result = yield* inner();
  yield result;
  yield 3;
}

const gen = outer();
const results = [];
let r = gen.next();
while (!r.done) {
  results.push(r.value);
  r = gen.next();
}
console.log(results.join(','));

export {};

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

const inc = x => x + 1;
const double = x => x * 2;
const square = x => x * x;

const f = compose(square, double, inc);
const g = pipe(square, double, inc);

console.log(f(2), g(2));

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

const add = n => x => x + n;
const mul = n => x => x * n;

const composed = compose(add(3), mul(2));
const piped = pipe(add(3), mul(2));

console.log(composed(5), piped(5));

const proto = { inherited: 'nope' };
const obj = Object.create(proto);
obj.b = 2;
obj[1] = 'one';
obj.a = 1;
Object.defineProperty(obj, 'hidden', { value: 'secret', enumerable: false });
obj[Symbol('sym')] = 'symbolValue';
console.log(
  Object.keys(obj).join(','),
  Object.values(obj).join(','),
  Object.entries(obj).length
);

function partial(fn, ...presetArgs) {
  return (...laterArgs) => fn(...presetArgs, ...laterArgs);
}

const add = (a, b, c) => a + b + c;
const addFive = partial(add, 5);
const addFiveTen = partial(addFive, 10);
console.log(addFiveTen(1), addFive(2, 3));

export {};

const nums = [40, 100, 1, 5, 25, 10];
nums.sort();
console.log(nums.join(' '));

class Range {
  #start; #end;
  constructor(start, end) { this.#start = start; this.#end = end; }
  [Symbol.iterator]() {
    let current = this.#start;
    const end = this.#end;
    return {
      next() {
        return current < end
          ? { value: current++, done: false }
          : { value: undefined, done: true };
      },
      [Symbol.iterator]() { return this; }
    };
  }
}

const range = new Range(1, 5);
const arr1 = [...range];
const arr2 = [...range];
const sum = arr1.reduce((a, b) => a + b, 0);
console.log(arr1.join(','), arr2.join(','), sum);

const log = [];

async function a() {
  log.push('a-start');
  await b();
  log.push('a-end');
}

async function b() {
  log.push('b-start');
  await Promise.resolve();
  log.push('b-end');
}

a();
log.push('sync-end');

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