How do I chain map and reduce in JavaScript?

How do I chain map and reduce in JavaScript?

You can chain map and reduce by calling them one after the other on an array. For example, you can first use map to transform the array and then use reduce to aggregate the results.

Can you show me a code example?

Sure! Here's a simple example:

const numbers = [1, 2, 3, 4];
const result = numbers.map(num => num * 2).reduce((acc, curr) => acc + curr, 0);
console.log(result); // Output: 20

This code doubles each number and then sums them up.

What if I want to filter the numbers before mapping?

You can add a filter before the map. Here's how:

const numbers = [1, 2, 3, 4];
const result = numbers.filter(num => num > 1).map(num => num * 2).reduce((acc, curr) => acc + curr, 0);
console.log(result); // Output: 14

This filters out numbers less than or equal to 1 before doubling and summing.

Are there any performance considerations when chaining these methods?

Yes, chaining methods can lead to performance overhead due to multiple iterations over the array. For large datasets, consider using a single loop to optimize performance.