時刻を短い形式、中程度の形式、長い形式、または完全な形式でフォーマットする方法

const formatter = new Intl.DateTimeFormat("en-US", {
  timeStyle: "short"
});

console.log(formatter.format(new Date("2025-03-15T14:30:00")));
// 出力: "2:30 PM"

const date = new Date("2025-03-15T14:30:45");

const shortFormatter = new Intl.DateTimeFormat("en-US", {
  timeStyle: "short"
});

const mediumFormatter = new Intl.DateTimeFormat("en-US", {
  timeStyle: "medium"
});

const longFormatter = new Intl.DateTimeFormat("en-US", {
  timeStyle: "long"
});

const fullFormatter = new Intl.DateTimeFormat("en-US", {
  timeStyle: "full"
});

console.log(shortFormatter.format(date));
// 出力: "2:30 PM"

console.log(mediumFormatter.format(date));
// 出力: "2:30:45 PM"

console.log(longFormatter.format(date));
// 出力: "2:30:45 PM PST"

console.log(fullFormatter.format(date));
// 出力: "2:30:45 PM Pacific Standard Time"

const date = new Date("2025-03-15T14:30:45");

const formatter = new Intl.DateTimeFormat("en-US", {
  dateStyle: "long",
  timeStyle: "short"
});

console.log(formatter.format(date));
// 出力: "March 15, 2025 at 2:30 PM"

const date = new Date("2025-03-15T14:30:45");

const combinations = [
  { dateStyle: "short", timeStyle: "short" },
  { dateStyle: "medium", timeStyle: "medium" },
  { dateStyle: "long", timeStyle: "long" },
  { dateStyle: "full", timeStyle: "full" }
];

combinations.forEach(options => {
  const formatter = new Intl.DateTimeFormat("en-US", options);
  console.log(formatter.format(date));
});

// 出力:
// "3/15/25, 2:30 PM"
// "Mar 15, 2025, 2:30:45 PM"
// "March 15, 2025 at 2:30:45 PM PST"
// "Saturday, March 15, 2025 at 2:30:45 PM Pacific Standard Time"

const date = new Date("2025-03-15T14:30:45");

const locales = ["en-US", "de-DE", "fr-FR", "ja-JP"];

locales.forEach(locale => {
  const shortFormatter = new Intl.DateTimeFormat(locale, {
    timeStyle: "short"
  });

  const longFormatter = new Intl.DateTimeFormat(locale, {
    timeStyle: "long"
  });

  console.log(`${locale}:`);
  console.log(`  Short: ${shortFormatter.format(date)}`);
  console.log(`  Long:  ${longFormatter.format(date)}`);
});

// Output:
// en-US:
//   Short: 2:30 PM
//   Long:  2:30:45 PM PST
// de-DE:
//   Short: 14:30
//   Long:  14:30:45 PST
// fr-FR:
//   Short: 14:30
//   Long:  14:30:45 UTC−8
// ja-JP:
//   Short: 14:30
//   Long:  14:30:45 PST

const formatter = new Intl.DateTimeFormat(navigator.language, {
  timeStyle: "short"
});

const meetings = [
  { title: "Team standup", time: new Date("2025-03-15T09:00:00") },
  { title: "Client call", time: new Date("2025-03-15T14:30:00") },
  { title: "Code review", time: new Date("2025-03-15T16:45:00") }
];

meetings.forEach(meeting => {
  console.log(`${meeting.title}: ${formatter.format(meeting.time)}`);
});

// Output:
// Team standup: 9:00 AM
// Client call: 2:30 PM
// Code review: 4:45 PM

const formatter = new Intl.DateTimeFormat(navigator.language, {
  timeStyle: "medium"
});

const activities = [
  { action: "User logged in", time: new Date("2025-03-15T09:15:23") },
  { action: "File uploaded", time: new Date("2025-03-15T09:18:47") },
  { action: "Settings updated", time: new Date("2025-03-15T09:22:11") }
];

activities.forEach(activity => {
  console.log(`${activity.action}: ${formatter.format(activity.time)}`);
});

// 出力:
// User logged in: 9:15:23 AM
// File uploaded: 9:18:47 AM
// Settings updated: 9:22:11 AM

const formatter = new Intl.DateTimeFormat(navigator.language, {
  timeStyle: "long",
  timeZone: "America/New_York"
});

const events = [
  { name: "Webinar starts", time: new Date("2025-03-15T14:00:00") },
  { name: "Registration closes", time: new Date("2025-03-15T13:30:00") }
];

events.forEach(event => {
  console.log(`${event.name}: ${formatter.format(event.time)}`);
});

// 出力:
// Webinar starts: 2:00:00 PM EST
// Registration closes: 1:30:00 PM EST

const formatter = new Intl.DateTimeFormat(navigator.language, {
  dateStyle: "full",
  timeStyle: "full"
});

const eventTime = new Date("2025-03-15T14:30:00");
console.log(formatter.format(eventTime));
// 出力例: "2025年3月15日土曜日 14時30分45秒 太平洋標準時"

const formatter = new Intl.DateTimeFormat("en-US", {
  timeStyle: "medium",
  hour: "2-digit"  // エラー: 組み合わせることができません
});

const formatter = new Intl.DateTimeFormat("en-US", {
  hour: "2-digit",
  minute: "2-digit",
  second: "2-digit"
});

console.log(formatter.format(new Date("2025-03-15T14:30:45")));
// 出力例: "02:30:45 PM"

const formatter = new Intl.DateTimeFormat("en-US", {
  dateStyle: "long",
  timeStyle: "long",
  timeZone: "America/New_York"
});

console.log(formatter.format(new Date("2025-03-15T14:30:00")));
// 出力例: "2025年3月15日 14:30:45 EST"

const formatter = new Intl.DateTimeFormat(navigator.language, {
  timeStyle: "short"
});

const time = new Date("2025-03-15T14:30:00");
console.log(formatter.format(time));
// 出力はユーザーのロケールによって異なる
// en-USの場合: "2:30 PM"
// de-DEの場合: "14:30"
// fr-FRの場合: "14:30"

const formatter = new Intl.DateTimeFormat(navigator.languages, {
  timeStyle: "medium"
});

const formatter = new Intl.DateTimeFormat(navigator.language, {
  timeStyle: "short"
});

const times = [
  new Date("2025-03-15T09:00:00"),
  new Date("2025-03-15T14:30:00"),
  new Date("2025-03-15T16:45:00")
];

times.forEach(time => {
  console.log(formatter.format(time));
});
// 出力:
// "9:00 AM"
// "2:30 PM"
// "4:45 PM"