Destructuring Assignment code example

Example 1: 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 2: 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 3: destructuring objects

({ a, b } = { a: 10, b: 20 });
console.log(a); // 10
console.log(b); // 20


// Stage 4(finished) proposal
({a, b, ...rest} = {a: 10, b: 20, c: 30, d: 40});
console.log(a); // 10
console.log(b); // 20
console.log(rest); // {c: 30, d: 40}

Example 4: destructuring assignment

Destructuring assignment is special syntax introduced in ES6, 
for neatly assigning values taken directly from an object.

const user = { name: 'John Doe', age: 34 };

const { name, age } = user;
// name = 'John Doe', age = 34

Example 5: javascript function destructuring

function f() {
  return [1, 2];
}

let a, b; 
[a, b] = f(); 
console.log(a); // 1
console.log(b); // 2

Example 6: js destructuring explained

const { identifier } = expression;