JavaScript Nullish Coalescing Operator

Nullish Coalescing Operator

Nullish coalescing operator는 왼쪽의 피연산자가 null이거나 undefined일 때, 오른쪽의 피연산자를 대신 반환하는 논리연산자이다.

 

JavaScript

const logic = null ?? true;

const mathresult = undefined ?? 99;

const customArray = [];

const judge01 = customArray ?? "exist?";

let vacant;

const judge02 = vacant ?? "exist?";

console.log(logic); // true

console.log(mathresult); // 99

console.log(judge01); // []

console.log(judge02); // exist?

 

 

 

 

 

|| 연산자

JavaScript

const test01 = false || "text";

console.log(test01); // text

const test02 = true || "text";

console.log(test02); // true

const test03 = 0 || 999;

console.log(test03); // 999

const test04 = null || 999;

console.log(test04); // 999

const test05 = false || false;

console.log(test05); // false

const test06 = null || false;

console.log(test06); // false

const test07 = 0 || null;

console.log(test07); // null