React JS ES6: destructuring

ReactJS destructuring

description

1 Overview

📘 Destructuring arrays

Array destructuring is a way to extract values from an array and assign them to separate variables.

It allows you to unpack the values of an array into separate variables.

---

2 Why do we need it

Array destructuring can be a useful tool for extracting values from arrays and assigning them to separate variables. It can make your code more concise and easier to read, especially when working with large or complex arrays.

Here is the old way of assigning array items to a variable:

App.js

const vehicles = ['mustang', 'f-150', 'expedition'];

// old way
const car = vehicles[0];
const truck = vehicles[1];
const suv = vehicles[2];

Here is the new way of assigning array items to a variable With destructuring:

App.js

const vehicles = ['mustang', 'f-150', 'expedition'];

const [car, truck, suv] = vehicles;

3 How to use destructuring

Here’s an example of array destructuring:

App.js

const arr = [1, 2, 3];
const [a, b, c] = arr;

console.log(a); // 1
console.log(b); // 2
console.log(c); // 3

You can also use destructuring to skip elements or assign default values:

App.js

const arr = [1, 2, 3];
const [a, , c] = arr;

console.log(a); // 1
console.log(c); // 3

const arr2 = [1];
const [a2, b2 = 2, c2 = 3] = arr2;

console.log(a2); // 1
console.log(b2); // 2
console.log(c2); // 3

In the first example, the second element of the arr array is skipped, and in the second example, default values are assigned to the b2 and c2 variables if the corresponding elements of the arr2 array are not present.

Array destructuring can be a convenient way to extract values from arrays and assign them to separate variables. It can make your code more concise and easier to read.

You can also use destructuring to skip elements or assign default values:

App.js

const arr = [1, 2, 3, 4];
const [a, , c, d] = arr;

console.log(a); // 1
console.log(c); // 3
console.log(d); // 4

const arr2 = [1];
const [a2, b2 = 2, c2 = 3, d2 = 4] = arr2;

console.log(a2); // 1
console.log(b2); // 2
console.log(c2); // 3
console.log(d2); // 4

4 More examples

4.1 Nested arrays

You can use destructuring to extract values from nested arrays:

App.js

const arr = [[1, 2], [3, 4]];
const [[a, b], [c, d]] = arr;

console.log(a); // 1
console.log(b); // 2
console.log(c); // 3
console.log(d); // 4

4.2 Rest syntax

The rest syntax allows you to capture the remaining elements of an array in a separate variable:

App.js

const arr = [1, 2, 3, 4, 5];
const [a, b, ...rest] = arr;

console.log(a); // 1
console.log(b); // 2
console.log(rest); // [3, 4, 5]

4.3 Swapping variables

You can use destructuring to easily swap the values of two variables:

App.js

let a = 1;
let b = 2;

[a, b] = [b, a];

console.log(a); // 2
console.log(b); // 1

4.4 Function arguments

You can use destructuring to specify function arguments:

App.js

function add([a, b]) {
  return a + b;
}

console.log(add([1, 2])); // 3

4.5 Object destructuring

You can also use destructuring with objects. Here’s an example:

App.js

const obj = {
  foo: 1,
  bar: 2
};

const { foo, bar } = obj;

console.log(foo); // 1
console.log(bar); // 2