destructuring an object code example

Example 1: javascript object destructuring

//simple example with object------------------------------
let obj = {name: 'Max', age: 22, address: 'Delhi'};
const {name, age} = obj;

console.log(name);
//expected output: "Max"

console.log(age);
//expected output: 22

console.log(address);
//expected output: Uncaught ReferenceError: address is not defined

// simple example with array-------------------------------
let a, b, rest;
[a, b] = [10, 20];

console.log(a);
// expected output: 10

console.log(b);
// expected output: 20

[a, b, ...rest] = [10, 20, 30, 40, 50];

console.log(rest);
// expected output: Array [30,40,50]

Example 2: Destructuring Assignment

const HIGH_TEMPERATURES = {
  yesterday: 75,
  today: 77,
  tomorrow: 80
};

//ES6 assignment syntax
const {today, tomorrow} = HIGH_TEMPERATURES;

//ES5 assignment syntax
const today = HIGH_TEMPERATURES.today;
const tomorrow = HIGH_TEMPERATURES.tomorrow;

console.log(today); // 77
console.log(tomorrow); // 80
console.log(yesterday); // "ReferenceError: yesterday is not defined" as it should be.

Example 3: object destructuring

const book = {
    title: 'Ego is the Enemy',
    author: 'Ryan Holiday',
    publisher: {
        name: 'Penguin',
        type: 'private'
    }
};

const {title: bookName =  'Ego', author, name: {publisher: { name }} = book, type: {publisher: { type }} = book } = book;

Example 4: object destructuring into this

const demo = { nextUrl: 'nextUrl', posts: 'posts' };

const target = {}; // replace target with this

({ nextUrl: target.nextUrl, posts: target.communityPosts } = demo);

console.log(target);

Example 5: javascript deconstruct object

const objA = {
 prop1: 'foo',
 prop2: {
   prop2a: 'bar',
   prop2b: 'baz',
 },
};

// Deconstruct nested props
const { prop1, prop2: { prop2a, prop2b } } = objA;

console.log(prop1);  // 'foo'
console.log(prop2a); // 'bar'
console.log(prop2b); // 'baz'

Example 6: js object destructuring with defaults

// Taken from top stack overflow answer

const { dogName = 'snickers' } = { dogName: undefined }
console.log(dogName) // what will it be? 'snickers'!

const { dogName = 'snickers' } = { dogName: null }
console.log(dogName) // what will it be? null!

const { dogName = 'snickers' } = { dogName: false }
console.log(dogName) // what will it be? false!

const { dogName = 'snickers' } = { dogName: 0 }
console.log(dogName) // what will it be? 0!