javascript destructuring assignment 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: 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: Object destructuring

Object Destructuring =>
//
   The destructuring assignment syntax is a JavaScript expression that makes it
possible to unpack values from arrays,
or properties from objects, into distinct variables.
//
example:
const user = {
    id: 42,
    is_verified: true
};

const {id, is_verified} = user;

console.log(id); // 42
console.log(is_verified); // true

Example 5: 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 6: javascript function destructuring

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

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