import 'core-js/actual';

Promise.try(() => 42).then(it => console.log(it)); // => 42

Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]

[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]

Iterator.concat([1, 2], function * (i) { while (true) yield i++; }(3))
  .drop(1).take(5)
  .filter(it => it % 2)
  .map(it => it ** 2)
  .toArray(); // => [9, 25]

structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])

import 'core-js/actual/promise';
import 'core-js/actual/set';
import 'core-js/actual/iterator';
import 'core-js/actual/array/from';
import 'core-js/actual/array/flat-map';
import 'core-js/actual/structured-clone';

Promise.try(() => 42).then(it => console.log(it)); // => 42

Array.from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]

[1, 2].flatMap(it => [it, it]); // => [1, 1, 2, 2]

Iterator.concat([1, 2], function * (i) { while (true) yield i++; }(3))
  .drop(1).take(5)
  .filter(it => it % 2)
  .map(it => it ** 2)
  .toArray(); // => [9, 25]

structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])

import Promise from 'core-js-pure/actual/promise';
import Set from 'core-js-pure/actual/set';
import Iterator from 'core-js-pure/actual/iterator';
import from from 'core-js-pure/actual/array/from';
import flatMap from 'core-js-pure/actual/array/flat-map';
import structuredClone from 'core-js-pure/actual/structured-clone';

Promise.try(() => 42).then(it => console.log(it)); // => 42

from(new Set([1, 2, 3]).union(new Set([3, 4, 5]))); // => [1, 2, 3, 4, 5]

flatMap([1, 2], it => [it, it]); // => [1, 1, 2, 2]

Iterator.concat([1, 2], function * (i) { while (true) yield i++; }(3))
  .drop(1).take(5)
  .filter(it => it % 2)
  .map(it => it ** 2)
  .toArray(); // => [9, 25]

structuredClone(new Set([1, 2, 3])); // => new Set([1, 2, 3])

import 'core-js/stable';
import 'regenerator-runtime/runtime';

import 'core-js/stable';

import 'core-js/modules/es.array.unscopables.flat';
import 'core-js/modules/es.array.unscopables.flat-map';
import 'core-js/modules/es.object.from-entries';
import 'core-js/modules/web.immediate';

import 'core-js/es';
import 'core-js/proposals/set-methods';
import 'core-js/full/set/map';

import 'core-js/modules/es.array.unscopables.flat';
import 'core-js/modules/es.array.unscopables.flat-map';
import 'core-js/modules/es.object.from-entries';
import 'core-js/modules/esnext.set.difference';
import 'core-js/modules/esnext.set.intersection';
import 'core-js/modules/esnext.set.is-disjoint-from';
import 'core-js/modules/esnext.set.is-subset-of';
import 'core-js/modules/esnext.set.is-superset-of';
import 'core-js/modules/esnext.set.map';
import 'core-js/modules/esnext.set.symmetric-difference';
import 'core-js/modules/esnext.set.union';

// first file:
let set = new Set([1, 2, 3]);

// second file:
let array = Array.of(1, 2, 3);

// first file:
import 'core-js/modules/es.array.iterator';
import 'core-js/modules/es.object.to-string';
import 'core-js/modules/es.set';

var set = new Set([1, 2, 3]);

// second file:
import 'core-js/modules/es.array.of';

var array = Array.of(1, 2, 3);

import from from 'core-js-pure/stable/array/from';
import flat from 'core-js-pure/stable/array/flat';
import Set from 'core-js-pure/stable/set';
import Promise from 'core-js-pure/stable/promise';

from(new Set([1, 2, 3, 2, 1]));
flat([1, [2, 3], [4, [5]]], 2);
Promise.resolve(32).then(x => console.log(x));

Array.from(new Set([1, 2, 3, 2, 1]));
[1, [2, 3], [4, [5]]].flat(2);
Promise.resolve(32).then(x => console.log(x));

const configurator = require('core-js/configurator');

configurator({
  useNative: ['Promise'],                                 // polyfills will be used only if natives are completely unavailable
  usePolyfill: ['Array.from', 'String.prototype.padEnd'], // polyfills will be used anyway
  useFeatureDetection: ['Map', 'Set'],                    // default behavior
});

require('core-js/actual');

let foo = { q: 1, w: 2 };
let bar = { e: 3, r: 4 };
let baz = { t: 5, y: 6 };
Object.assign(foo, bar, baz); // => foo = { q: 1, w: 2, e: 3, r: 4, t: 5, y: 6 }

Object.is(NaN, NaN); // => true
Object.is(0, -0);    // => false
Object.is(42, 42);   // => true
Object.is(42, '42'); // => false

function Parent() { /* empty */ }
function Child() { /* empty */ }
Object.setPrototypeOf(Child.prototype, Parent.prototype);
new Child() instanceof Child;  // => true
new Child() instanceof Parent; // => true

({
  [Symbol.toStringTag]: 'Foo',
}).toString(); // => '[object Foo]'

Object.keys('qwe'); // => ['0', '1', '2']
Object.getPrototypeOf('qwe') === String.prototype; // => true

Object.values({ a: 1, b: 2, c: 3 });  // => [1, 2, 3]
Object.entries({ a: 1, b: 2, c: 3 }); // => [['a', 1], ['b', 2], ['c', 3]]

for (let [key, value] of Object.entries({ a: 1, b: 2, c: 3 })) {
  console.log(key);   // => 'a', 'b', 'c'
  console.log(value); // => 1, 2, 3
}

// Shallow object cloning with prototype and descriptors:
let copy = Object.create(Object.getPrototypeOf(object), Object.getOwnPropertyDescriptors(object));
// Mixin:
Object.defineProperties(target, Object.getOwnPropertyDescriptors(source));

const map = new Map([['a', 1], ['b', 2]]);
Object.fromEntries(map); // => { a: 1, b: 2 }

class Unit {
  constructor(id) {
    this.id = id;
  }
  toString() {
    return `unit${ this.id }`;
  }
}

const units = new Set([new Unit(101), new Unit(102)]);

Object.fromEntries(units.entries()); // => { unit101: Unit { id: 101 }, unit102: Unit { id: 102 } }

Object.hasOwn({ foo: 42 }, 'foo'); // => true
Object.hasOwn({ foo: 42 }, 'bar'); // => false
Object.hasOwn({}, 'toString');     // => false

Object.groupBy([1, 2, 3, 4, 5], it => it % 2); // => { 1: [1, 3, 5], 0: [2, 4] }

(function foo() { /* empty */ }).name; // => 'foo'

console.log.bind(console, 42)(43); // => 42 43

const error1 = new TypeError('Error 1');
const error2 = new TypeError('Error 2');
const aggregate = new AggregateError([error1, error2], 'Collected errors');
aggregate.errors[0] === error1; // => true
aggregate.errors[1] === error2; // => true

const cause = new TypeError('Something wrong');
const error = new TypeError('Here explained what`s wrong', { cause });
error.cause === cause; // => true

Error.prototype.toString.call({ message: 1, name: 2 }) === '2: 1'; // => true

Error.isError(new Error('error')); // => true
Error.isError(new TypeError('error')); // => true
Error.isError(new DOMException('error')); // => true

Error.isError(null); // => false
Error.isError({}); // => false
Error.isError(Object.create(Error.prototype)); // => false

Array.from(new Set([1, 2, 3, 2, 1]));        // => [1, 2, 3]
Array.from({ 0: 1, 1: 2, 2: 3, length: 3 }); // => [1, 2, 3]
Array.from('123', Number);                   // => [1, 2, 3]
Array.from('123', it => it ** 2);            // => [1, 4, 9]

Array.of(1);       // => [1]
Array.of(1, 2, 3); // => [1, 2, 3]

let array = ['a', 'b', 'c'];

for (let value of array) console.log(value);          // => 'a', 'b', 'c'
for (let value of array.values()) console.log(value); // => 'a', 'b', 'c'
for (let key of array.keys()) console.log(key);       // => 0, 1, 2
for (let [key, value] of array.entries()) {
  console.log(key);                                   // => 0, 1, 2
  console.log(value);                                 // => 'a', 'b', 'c'
}

function isOdd(value) {
  return value % 2;
}
[4, 8, 15, 16, 23, 42].find(isOdd);      // => 15
[4, 8, 15, 16, 23, 42].findIndex(isOdd); // => 2
[1, 2, 3, 4].findLast(isOdd);            // => 3
[1, 2, 3, 4].findLastIndex(isOdd);       // => 2

Array(5).fill(42); // => [42, 42, 42, 42, 42]

[1, 2, 3, 4, 5].copyWithin(0, 3); // => [4, 5, 3, 4, 5]

[1, 2, 3].includes(2);        // => true
[1, 2, 3].includes(4);        // => false
[1, 2, 3].includes(2, 2);     // => false

[NaN].indexOf(NaN);           // => -1
[NaN].includes(NaN);          // => true
Array(1).indexOf(undefined);  // => -1
Array(1).includes(undefined); // => true

[1, [2, 3], [4, 5]].flat();    // => [1, 2, 3, 4, 5]
[1, [2, [3, [4]]], 5].flat();  // => [1, 2, [3, [4]], 5]
[1, [2, [3, [4]]], 5].flat(3); // => [1, 2, 3, 4, 5]

[{ a: 1, b: 2 }, { a: 3, b: 4 }, { a: 5, b: 6 }].flatMap(it => [it.a, it.b]); // => [1, 2, 3, 4, 5, 6]

[1, 2, 3].at(1);  // => 2
[1, 2, 3].at(-1); // => 3

const sequence = [1, 2, 3];
sequence.toReversed(); // => [3, 2, 1]
sequence; // => [1, 2, 3]

const initialArray = [1, 2, 3, 4];
initialArray.toSpliced(1, 2, 5, 6, 7); // => [1, 5, 6, 7, 4]
initialArray; // => [1, 2, 3, 4]

const outOfOrder = [3, 1, 2];
outOfOrder.toSorted(); // => [1, 2, 3]
outOfOrder; // => [3, 1, 2]

const correctionNeeded = [1, 1, 3];
correctionNeeded.with(1, 2); // => [1, 2, 3]
correctionNeeded; // => [1, 1, 3]

await Array.fromAsync((async function * () { yield * [1, 2, 3]; })(), i => i ** 2); // => [1, 4, 9]

[1, 2, 3, 4, 5, 6, 7].values()
  .drop(1)
  .take(5)
  .filter(it => it % 2)
  .map(it => it ** 2)
  .toArray(); // => [9, 25]

Iterator.from({
  next: () => ({ done: Math.random() > 0.9, value: Math.random() * 10 | 0 }),
}).toArray(); // => [7, 6, 3, 0, 2, 8]

Iterator.concat([0, 1].values(), [2, 3], function * () {
  yield 4;
  yield 5;
}()).toArray(); // => [0, 1, 2, 3, 4, 5]

for (let value of 'a𠮷b') {
  console.log(value); // => 'a', '𠮷', 'b'
}

'foobarbaz'.includes('bar');      // => true
'foobarbaz'.includes('bar', 4);   // => false
'foobarbaz'.startsWith('foo');    // => true
'foobarbaz'.startsWith('bar', 3); // => true
'foobarbaz'.endsWith('baz');      // => true
'foobarbaz'.endsWith('bar', 6);   // => true

'string'.repeat(3); // => 'stringstringstring'

'hello'.padStart(10);         // => '     hello'
'hello'.padStart(10, '1234'); // => '12341hello'
'hello'.padEnd(10);           // => 'hello     '
'hello'.padEnd(10, '1234');   // => 'hello12341'

'𠮷'.codePointAt(0); // => 134071
String.fromCodePoint(97, 134071, 98); // => 'a𠮷b'

let name = 'Bob';
String.raw`Hi\n${ name }!`;           // => 'Hi\\nBob!' (ES2015 template string syntax)
String.raw({ raw: 'test' }, 0, 1, 2); // => 't0e1s2t'

'foo'.bold();                      // => '<b>foo</b>'
'bar'.anchor('a"b');               // => '<a name="a&quot;b">bar</a>'
'baz'.link('https://example.com'); // => '<a href="https://example.com">baz</a>'

RegExp('.', 's').test('\n'); // => true
RegExp('.', 's').dotAll;     // => true

RegExp('foo:(?<foo>\\w+),bar:(?<bar>\\w+)').exec('foo:abc,bar:def').groups; // => { foo: 'abc', bar: 'def' }

'foo:abc,bar:def'.replace(RegExp('foo:(?<foo>\\w+),bar:(?<bar>\\w+)'), '$<bar>,$<foo>'); // => 'def,abc'

// eslint-disable-next-line regexp/no-useless-flag -- example
RegExp(/./g, 'm'); // => /./m

/foo/.flags;   // => ''
/foo/gi.flags; // => 'gi'

RegExp('foo', 'y').sticky; // => true

const text = 'First line\nSecond line';
const regex = RegExp('(?<index>\\S+) line\\n?', 'y');

regex.exec(text).groups.index; // => 'First'
regex.exec(text).groups.index; // => 'Second'
regex.exec(text);    // => null

'foo'.match({ [Symbol.match]: () => 1 });     // => 1
'foo'.replace({ [Symbol.replace]: () => 2 }); // => 2
'foo'.search({ [Symbol.search]: () => 3 });   // => 3
'foo'.split({ [Symbol.split]: () => 4 });     // => 4

RegExp.prototype.toString.call({ source: 'foo', flags: 'bar' }); // => '/foo/bar'

'   hello   '.trimLeft();  // => 'hello   '
'   hello   '.trimRight(); // => '   hello'
'   hello   '.trimStart(); // => 'hello   '
'   hello   '.trimEnd();   // => '   hello'

for (let { groups: { number, letter } } of '1111a2b3cccc'.matchAll(RegExp('(?<number>\\d)(?<letter>\\D)', 'g'))) {
  console.log(number, letter); // => 1 a, 2 b, 3 c
}

'Test abc test test abc test.'.replaceAll('abc', 'foo'); // -> 'Test foo test test foo test.'

'abc'.at(1);  // => 'b'
'abc'.at(-1); // => 'c'

'a💩b'.isWellFormed();      // => true
'a\uD83Db'.isWellFormed();  // => false

'a💩b'.toWellFormed();      // => 'a💩b'
'a\uD83Db'.toWellFormed();  // => 'a�b'