Optional Chaining - ES2020 - Chrome 80+

optional_chaining.js

// Use case: when dealing with deeply nested objects.
// example: { dog : { cat : { parrot : peacock }}}

let obj = { dog : { cat : { parrot : 'peacock' }}};

let iWantPeacock = obj.dog.cat.parrot; //can throw an error


// Alternatively, one can do preliminary checks before the assignment

if(obj && obj.dog && obj.dog.cat) {
  let iWantPeacock = obj.dog.cat.parrot 
}

// Now an easier and graceful way of doing this is called optional chaining
// it will return undefined if an error was thrown, else it will return the string peacock
let iWantPeacock = obj?.dog?.cat?.parrot 


//This new syntax is part of ES2020, now supported natively in chrome80+, firefox74+, safari13.1+, node14+
//more info: https://v8.dev/features/optional-chaining