Array Methods: forEach, map, filter, find

In this lesson, we will introduce four methods used for iterating over array elements: forEach, map, filter, and find.

forEach executes a provided function once for each array element.

For example, using forEach, you can sequentially print out all the items in an array.

Copy
const fruits = ['Apple', 'Banana', 'Cherry'];

fruits.forEach(function (fruit) {
  console.log(fruit);
});

map applies the given function to each item of the array and creates a new array with the results.

For instance, you can use map to double all numbers in an array.

Copy
const numbers = [1, 2, 3, 4];

const doubled = numbers.map(function (num) {
  return num * 2;
});

console.log(doubled); // [2, 4, 6, 8]

filter creates a new array with all items that meet the given condition.

For example, you can use filter to extract only even numbers.

Copy
const numbers = [1, 2, 3, 4];

const evens = numbers.filter(function (num) {
  return num % 2 === 0;
});

console.log(evens); // [2, 4]

find returns the first item in an array that satisfies the provided condition.

If no matching item is found, it returns undefined.

For example, in the given array, you can find the first number greater than 10.

Copy
const numbers = [5, 12, 8, 130, 44];

const found = numbers.find(function (num) {
  return num > 10;
});

console.log(found); // 12