JavaScript operator

Two punctuation operators (Nullish Coalescing Operator)

The two punctuation operators return the value of the right term only if the value of the left term is null or undefined; otherwise, they return the value of the left term. // // 0은 포함되지 않음

const a = null;
const b = undefined;
const c = 0;
const d = '';
const e = false;

console.log(a ?? 'default'); // 'default'
console.log(b ?? 'default'); // 'default'
console.log(c ?? 'default'); // 0 // 0 not included
console.log(d ?? 'default'); // ''
console.log(e? 'default'); // false

When looking for true values from the left, you can use the ||(logical OR) operator to find true values from the left.

To find true values from the left, connect variables successively with the | operator, and proceed from left to right until you get the desired value. Returns the first value evaluated as true.

var value1 = false;
var value2 = "hey";
var value3 = true;
var value4 = 'Hello';
var value5 = 0;

var result = value1 || value2 || value3 || value4 || value5;// value2 is assigned "hey" When looking for false values from the left of 

Use the && operator to find false values from the left.

To find false values from the left, connect variables successively with the && operator, and proceed from left to right until you get the desired value. Returns the first value evaluated as false.

var value1 = true;
var value2 = "hey";
var value3 = "";
var value4 = 'Hello';
var value5 = 0;

var result = value1 && value2 && value3 && value4 && value5; // value3의 값 ""이 할당됨

물결 두 개 연산자 (Double Tilde)

The two wave operators are operators that leave a given number with no more than a decimal point and leave only an integer part.

let numA = 5.5;
console.log(~~numA); // 5

let numB = -10 / 3;
console.log(~~numB); // -3