Web API

/* Assuming that self.crypto.randomUUID() is available */
 
let uuid = self.crypto.randomUUID();
console.log(uuid); // for example "36b8f84d-df4e-4d49-b662-bcde71a8764f"

const currentDateKR =  new Intl.DateTimeFormat('ko-KR').format(new Date()) // 2023.2.16
const currentDateEN =  new Intl.DateTimeFormat('en-US').format(new Date()) // 2/16/2023
 
const options = {
  weekday: 'long',
  year: 'numeric',
  month: 'long',
  day: 'numeric'
}
 
// with options
const currentDateKRWithOptions =  new Intl.DateTimeFormat('ko-KR', options).format(new Date()) // 2023년 2월 16일 목요일
const currentDateENWithOptions =  new Intl.DateTimeFormat('en-US', options).format(new Date()) // Thursday, February 16, 2023

const money = 123456789
const koCurrency = new Intl.NumberFormat('ko-KR', {style: 'currency', currency: 'KRW'}).format(money) // '₩123,456,789'
const enCurrency = new Intl.NumberFormat('en-US', {style: 'currency', currency: 'USD'}).format(money) // '$123,456,789.00'

const t0 = performance.now();
 
doSomething();
 
const t1 = performance.now();
console.log(`Call to doSomething took ${t1 - t0} milliseconds.`);

const audio = document.querySelector("audio");
 
// Handle page visibility change:
// - If the page is hidden, pause the video
// - If the page is shown, play the video
document.addEventListener("visibilitychange", () => {
  if (document.hidden) {
    audio.pause();
  } else {
    audio.play();
  }
});