Date

JavaScript Date Date

JavaScript Java 2 Unix 1970 1 1 00:00:00 1970 1 1 00:00:00 1970 1 1 0 UTC

Date -100,000,000 100,000,000

Date

const dateObjectName = new Date([parameters]);

dateObjectName Date

new Date

parameters

• : today = new Date();
• YYYY-MM-DDTHH:mm:ss.sssZ xmas95 = new Date("1995-12-25")
• xmas95 = new Date(1995, 11, 25)
• xmas95 = new Date(1995, 11, 25, 9, 30, 0);

Date

Date

• Date
• Date
• Date
• UTC Date

getDay setDay

• : 0 59
• : 0 23
• : 0 6
• : 1 31
• : 0 1 11 12
• : 1900

const xmas95 = new Date("1995-12-25");

xmas95.getMonth() 11 xmas95.getFullYear() 1995

getTime setTime getTime Date

const today = new Date();
const endYear = new Date(1995, 11, 31, 23, 59, 59, 999); // 
endYear.setFullYear(today.getFullYear()); // 
const msPerDay = 24 * 60 * 60 * 1000; // 
let daysLeft = (endYear.getTime() - today.getTime()) / msPerDay;
daysLeft = Math.round(daysLeft); // 

today Date endYear Date 1 today endYear getTime

parse Date parse setTime ipoDate

const ipoDate = new Date();
ipoDate.setTime(Date.parse("Aug 9, 1995"));

JSClock()

function JSClock() {
  const time = new Date();
  const hour = time.getHours();
  const minute = time.getMinutes();
  const second = time.getSeconds();
  let temp = String(hour % 12);
  if (temp === "0") {
    temp = "12";
  }
  temp += (minute < 10 ? ":0" : ":") + minute;
  temp += (second < 10 ? ":0" : ":") + second;
  temp += hour >= 12 ? " P.M." : " A.M.";
  return temp;
}

JSClock time Date time getHours getMinutesgetSeconds hourminutesecond

4 temp hour 12 (hour - 12) hour hour 0 12

minute temp minute 10 temp

hour 12 "P.M." temp "A.M." temp