What are the differences between map, filter, and forEach in JavaScript?

What are the differences between map, filter, and forEach in JavaScript?

The map, filter, and forEach methods are all used to iterate over arrays, but they serve different purposes. map creates a new array by applying a function to each element, filter creates a new array with elements that pass a test, and forEach executes a function on each element without returning a new array.

Can you give me examples of each method?

Sure! For map, you can use it like this: const doubled = arr.map(num => num * 2);. For filter, it would be: const evens = arr.filter(num => num % 2 === 0);. And for forEach, you can do: arr.forEach(num => console.log(num));.

When should I use each of these methods?

Use map when you want to transform data, filter when you need to select specific elements, and forEach when you want to perform an action on each element without needing a new array.

Are there any performance differences between them?

Yes, there can be performance differences. Generally, forEach is faster for simple iterations, while map and filter may be slower due to the creation of new arrays. However, the difference is often negligible for small arrays.