What is the difference between the array methods filter and forEach?

The array method filter creates and returns a new array containing only those elements of the original array for which the predicate function returns true. It does not modify the original array.

The forEach method simply executes a specified function for each element of the array, without returning a new array and without modifying the original array (unless the function explicitly changes the elements).

Example:

const arr = [1, 2, 3, 4];

const filtered = arr.filter(x => x % 2 === 0); // [2, 4]

arr.forEach(x => console.log(x)); // Will output 1, 2, 3, 4 in sequence

Thus, filter is used to create a new filtered array, while forEach is used to perform side effects with the elements without creating a new array.