What are some common mistakes when using map and filter in JavaScript?

What are some common mistakes when using map and filter in JavaScript?

One common mistake is using map when you actually want to filter items. Map transforms each element, while filter removes elements based on a condition.

Can you give me an example of that?

Sure! If you have an array of numbers and you want to get only the even numbers, you should use filter, not map. Using map would return an array of the same length with transformed values.

What about using them together?

Using them together can be powerful, but a mistake is not chaining them correctly. For example, you might want to filter first and then map the results.

What are some performance considerations?

Chaining map and filter can lead to performance issues with large arrays. It's often better to combine the operations into a single loop if possible.