# .map()
Creates a new array by applying a given function to every element in an existing array. It does not modify the original array but instead returns a new array with transformed values.
let numbers = [1, 2, 3, 4, 5];
let doubled = numbers.map(num => num * 2);let users = [
{ name: "John", age: 56},
{ name: "Roman", age: 50}
];
let username = users.map(user =>
user.name);# .filter()
Creates a new array containing elements, that pass a specific condition. When the condition returns true, the element is included in the new array.
let numbers = [1, 2, 3, 4, 5];
let newArr = numbers.filter(num =>
num > 3);# .reduce()
Used to “reduce” an array to a single value by executing a reducer function (that we provide). This results in a final result.
let numbers = [1, 2, 3, 4, 5];
// note: it starts with 0, since accumulator (acc) = 0
// Then it takes: 0 + 1 + 2 + ...
let sum = numbers.reduce((acc, curr) => acc + curr, 0);