optional chaining

//Optional CHaining
const bob = {
	name: 'Julia',
  	age: 20,
}

const anna = {
	name:'Julia',
  	age:20,
  	job:{
    	title:'software engineer'
    }
}

//Bad 
//job이 있을수도 있고 없을수도 있고, 타이틀을 보여줘야한다
functioin displayJobTitle (person){
	if(person.job && person.job.title) {
    	console.log(person.job.title);
    }
}

// Good
function displayJobTitle (person){
	if(person.job?.title){
     	console.log(person.job.title);  
     }
}

// optional chaining , nullish 
function displayJobTitle(person){
	const title = person.job?.title ?? 'No Job yet';
    console.log(title);
}