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

Can you explain the differences between filter, reduce, and map in JavaScript?

Sure! In JavaScript, filter, reduce, and map are array methods used for different purposes. filter creates a new array with all elements that pass a test, map creates a new array by applying a function to each element, and reduce executes a reducer function on each element to reduce the array to a single value.

Can you give me an example of how each of these methods works?

Of course! For filter, if you have an array of numbers and want to keep only the even ones, you can use array.filter(num => num % 2 === 0). For map, if you want to double each number, you can use array.map(num => num * 2). And for reduce, if you want to sum all numbers, you can use array.reduce((acc, num) => acc + num, 0).

What would happen if I tried to use them incorrectly?

If used incorrectly, you might get unexpected results. For example, using filter with a function that doesn't return a boolean will lead to an empty array. Similarly, using reduce without an initial value can cause errors if the array is empty.

Are there any performance differences between these methods?

Yes, there can be performance differences. Generally, map and filter create new arrays, which can be more memory-intensive, while reduce can be more efficient if you're combining values into a single result. However, the actual performance can depend on the size of the array and the complexity of the operations.