Callbacks and Higher-Order Functions

To filter out elements from an array
To execute a reducer function on each element of the array, resulting in a single output value
The Array.reduce() method executes a reducer function on each element of the array, resulting in a single output value. The reducer function takes four arguments: accumulator, current value, current index, and the source array. reduce() is particularly powerful for transforming an array into any other type of value (like an object, number, or string). It's commonly used for summing numbers, concatenating strings, or building composite data structures from array data.
To modify each element of an array in place
To check if at least one element in an array passes a given test