When are the methods array.forEach and array.map used?

forEach is used to iterate over array elements and perform an action for each element. It does not create a new array and does not return a value. Suitable for performing side effects (e.g., logging, DOM manipulation).

map is used to transform each element of an array and create a new array from the transformation results. It always returns a new array of the same length. Suitable for obtaining a new set of data based on an existing one.

Example:

const numbers = [1, 2, 3];

// Using forEach to output each element
numbers.forEach((number) => {
  console.log(number); // 1, 2, 3
});

// Using map to create an array of squares of numbers
const squares = numbers.map((number) => {
  return number * number;
});
console.log(squares); // [1, 4, 9]

Comparison table:

Feature	forEach	map
Return value	undefined	New array
Purpose	Perform actions for each element	Transform elements, create a new array
Modifies original array	No (unless the element itself is changed)	No