exercise

index.js

// 9. 
const removeEven = (arr) => {
	return arr.filter((el) => el % 2 !== 0);
};

console.log(removeEven([1, 2, 4, 5, 10, 6, 3]));

// 10.
const capitalize = (words) => {
	return words.map((el) => el.charAt(0).toUpperCase() + el.slice(1));
};

console.log(capitalize(['Hello', 'there!', 'How', 'are', 'you', 'doing?']));

// 11.
const evenOdd = (numbers) => {
	return numbers.map((number) => (number % 2 === 0 ? 'even' : 'odd'));
};

console.log(evenOdd([1, 2, 3, 4, 5]));

//12.
const onlyAbove40 = (familyMembers) => {
	return familyMembers.reduce((acc, cur) => {
		if (cur.age > 40) acc.push(cur.familyMember);

		return acc;
	}, []);
};

console.log(
	onlyAbove40([
		{
			familyMember: 'Uncle',
			age: 52,
			location: 'San Diego, CA',
		},
		{
			familyMember: 'Grandpa',
			age: 84,
			location: 'San Francisco, CA',
		},
		{
			familyMember: 'Sister',
			age: 19,
			location: 'New York, NY',
		},
	])
);

// 13.
const add = (numbers) => {
	return numbers.reduce((acc, cur) => (acc += cur), 0);
};

console.log(add([1, 2, 3, 4, 5]));

// 14.
const toObject = (strings) => {
	return strings.reduce((acc, cur) => ({ ...acc, [cur]: true }), {});
};

console.log(toObject(['a', 'b', 'c', 'd']));

// 15.
const isSubset = (arr1, arr2) => {
	if (arr1.length > arr2.length) return false;

	// for (let i = 0; i < arr1.length; i++) {
	// 	for (let j = 0; j < arr2.length; j++) {
	// 		if (arr1[i] === arr2[j]) {
	// 			break;
	// 		}
	// 		if (j === arr2.length - 1) return false;
	// 	}
	// }

	const arr2Obj = arr2.reduce((acc, cur) => ({ ...acc, [cur]: true }), {});
	for (let i = 0; i < arr1.length; i++) {
		if (!arr2Obj[arr1[i]]) return false;
	}

	return true;
};

console.log(isSubset(['abc', 17, 'def'], ['def', 'abc', null, 17, 24]));

// 16. 
const findMinimum = (arr) => {
	// return arr.sort((a, b) => a - b)[0];
	return Math.min(...arr);
};

console.log(findMinimum([9, 2, 3, 6]));

// 17.
const reArrange = (arr) => {
	return arr.sort();
};

console.log(reArrange([10, -1, 20, 4, 5, -9, -6]));

https://gist.github.com/hoapha1009/3fa52b7a0c0598edcc195f474976e55b#file-index-js-L2
mình có thể sử dụng rút gọn đi return

https://gist.github.com/hoapha1009/3fa52b7a0c0598edcc195f474976e55b#file-index-js-L23
bài dùng dùng filter sẽ đơn giản hơn