gist to show how destruction works for nested object

nested_object_destruction.js

// extract single prop with same name
const user = {
  id: 339,
  name: 'Fred',
  age: 42
};
const {name} = user;
console.log(name); //prints: Fred


// extract single prop with different name

const user = {
  id: 339,
  name: 'Fred',
  age: 42
};
const {name: callSign} = user;
console.log(callSign); //prints: Fred


// extract nested prop from object

const user = {
  id: 339,
  name: 'Fred',
  age: 42,
  education: {
    degree: 'Masters'
  }
};
const {education: {degree}} = user;
console.log(degree); //prints: Masters

// if nested object is not available destruction will throw error
const user = {
  id: 339,
  name: 'Fred',
  age: 42
};
const {education: {degree}} = user;  // TypeError: Cannot match against 'undefined' or 'null'.

// avoids type error when nested object is not present
const user = {
  id: 339,
  name: 'Fred',
  age: 42
};
const {education: {school: {name} = {}} = {}} = user;
console.log(name); //prints: undefined

// Approach-1 to add default school name
const user = {
  id: 339,
  name: 'Fred',
  age: 42
};
const {education: {school: {name = 'Dunno'} = {}} = {}} = user;
console.log(name); //prints: Dunno

// Approach-2  to add default school name
const user = {
  id: 339,
  name: 'Fred',
  age: 42
};
const {education: {school: {name}} = {school: {name: 'Dunno'}} = user;
console.log(name); //prints: Dunno