Please implement the below function in Javascript and name the source file as h2.js. Use test file h2.test.js to test your code. You need to install the jest before testing your code.

A chainable function say() that accepts one string per call, but when called without arguments, returns the words previously passed, in order, separated by a single space.

h2.test.js

const { change, stripQuotes, scramble, say, powers, interleave, } = require('./h2'); // Helper for the scramble tests function anagramsOfEachOther(s, t) { return s.split('').sort().join('') === t.split('').sort().join(''); } // Helper for testing the callbacky problems function generatorToArray(generator, ...args) { const result = []; generator(...args, (item) => result.push(item)); return result; } describe('change', () => { it('handles zero', () => { expect(change(0)).toEqual([0, 0, 0, 0]); }); it('computes answers for small integer values fine', () => { expect(change(97)).toEqual([3, 2, 0, 2]); expect(change(8)).toEqual([0, 0, 1, 3]); expect(change(250)).toEqual([10, 0, 0, 0]); expect(change(144)).toEqual([5, 1, 1, 4]); expect(change(97)).toEqual([3, 2, 0, 2]); }); it('handles large values', () => { // This test only passes if the solution is efficient expect(change(100000000000)).toEqual([4000000000, 0, 0, 0]); }); it('throws the proper exception for negative arguments', () => { expect(() => change(-50)).toThrow(RangeError); }); }); describe('stripQuotes', () => { it('works on the empty string', () => { expect(stripQuotes('')).toEqual(''); }); it('strips quotes properly for non-empty strings', () => { expect(stripQuotes('Hello, world')).toEqual('Hello, world'); expect(stripQuotes('"\'')).toEqual(''); expect(stripQuotes('a"""\'\'"z')).toEqual('az'); }); }); describe('scramble', () => { it('scrambles properly', () => { ['a', 'rat', 'JavaScript testing', '', 'zzz', '^*^*)^'].forEach((s) => { expect(anagramsOfEachOther(s, scramble(s))).toBeTruthy(); }); }); it('is really random (produces all permutations)', () => { const possibilities = new Set('ABC ACB BAC BCA CAB CBA'.split(' ')); for (let i = 0; i < 200; i += 1) { possibilities.delete(scramble('ABC')); } expect(possibilities.size).toBe(0); }); }); describe('say', () => { it('works when there are no words', () => { expect(say()).toBe(''); }); it('works when there are words', () => { expect(say('hi')()).toBe('hi'); expect(say('hi')('there')()).toBe('hi there'); expect(say('hello')('my')('name')('is')('Colette')()).toBe('hello my name is Colette'); }); }); describe('powers', () => { it('generates sequences of powers properly', () => { expect(generatorToArray(powers, 2, -5)).toEqual([]); expect(generatorToArray(powers, 7, 0)).toEqual([]); expect(generatorToArray(powers, 3, 1)).toEqual([1]); expect(generatorToArray(powers, 2, 63)).toEqual([1, 2, 4, 8, 16, 32]); expect(generatorToArray(powers, 2, 64)).toEqual([1, 2, 4, 8, 16, 32, 64]); }); }); describe('interleave', () => { it('interleaves properly', () => { expect(interleave([])).toEqual([]); expect(interleave([1, 4, 6])).toEqual([1, 4, 6]); expect(interleave([], 2, 3)).toEqual([2, 3]); expect(interleave([1], 9)).toEqual([1, 9]); expect(interleave([8, 8, 3, 9], 1)).toEqual([8, 1, 8, 3, 9]); expect(interleave([2], 7, '8', {})).toEqual([2, 7, '8', {}]); }); });