Arrays and objects are the workhorses of JavaScript data. Master array methods (map, filter, reduce), string operations, and common algorithms like searching and sorting. Remember: arrays are O(1) access and O(n) insertion/deletion.

• map — transform each element
• filter — keep elements that match a condition
• reduce — combine elements into a single value

const arr = [1, 2, 3, 4, 5];

const doubled = arr.map(x => x * 2);
console.log(doubled); // [2, 4, 6, 8, 10]

const evens = arr.filter(x => x % 2 === 0);
// ...

Use map, filter, and reduce on the provided array and print the results.

Arrays and objects are the workhorses of JavaScript data. Master array methods (map, filter, reduce), string operations, and common algorithms like searching and sorting. Remember: arrays are O(1) access and O(n) insertion/deletion.

• map — transform each element
• filter — keep elements that match a condition
• reduce — combine elements into a single value

const arr = [1, 2, 3, 4, 5];

const doubled = arr.map(x => x * 2);
console.log(doubled); // [2, 4, 6, 8, 10]

const evens = arr.filter(x => x % 2 === 0);
// ...

Use map, filter, and reduce on the provided array and print the results.