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Practice

Array Methods: forEach, map, filter, find

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


forEach​

forEach executes a provided function once for each array element.

For example, using forEach, you can sequentially log all items in an array.

forEach Example
const fruits = ['Apple', 'Banana', 'Cherry'];

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

map​

map applies a given function to each array element and returns a new array with the results.

For example, using map, you can double all the numbers in an array.

map Example
const numbers = [1, 2, 3, 4];

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

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

filter​

filter creates a new array with all elements that pass a test implemented by the provided function.

For example, using filter, you can select only the even numbers from an array.

filter Example
const numbers = [1, 2, 3, 4];

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

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

find​

find returns the first element in the array that satisfies the provided testing function.

If no elements satisfy the testing function, undefined is returned.

For example, using find, you can locate the first number greater than 10 in an array.

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

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

console.log(found); // 12

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