자바스크립트 Nullish, optional

Nullish coalescing operator

function printMessage(text) {
  let message = text;
  if (text == null || text == undefinde) {
      message = "Noting to display;
  }
  console.log(message);
}

function print message(text) {
const message = text ?? "noting to display"
console.log(message)
```;
}

기본 파라미터일때는 null 인 경우는 안됨

Logicla or operator ||

leftExpr || rightExpr 
leftEXpr 가 거짓일때 rightExpr 실행
(false, 0, nan, -0, "", undefinde, null)



function print message(text) {
  const message = text || "noting to display"
  console.log(message);
}

const result = getInitialState() ?? fetchFromServer();
console.log(result);

function getInitialState() {
	return null;
}

function fetchFromServer() {
	return "Hiya from ';
}


function displayJobTitle(person) {
  if (person.job && person.job.title) {
  	console.log(person.job.title);
  }
}

=> 

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

function displayJobTitle(person) {
  const title = personjob?.title ?? "No Job Yet";
  console.log(title)
}