What are common mistakes when using map and forEach in JavaScript?

What are common mistakes when using map and forEach in JavaScript?

Some common mistakes include using forEach when you need to return a new array, or forgetting to return a value in map.

Can you explain why using forEach instead of map is a mistake?

Using forEach doesn't return a new array, so if you need to transform data, map is the correct choice.

What happens if I forget to return a value in map?

If you forget to return a value in map, the resulting array will contain 'undefined' for each element.

Are there performance differences between map and forEach?

Yes, map can be more efficient for creating new arrays, while forEach is better for executing side effects.