local()

Explicitly converts the instance to local time. This method ensures the date is represented in the local timezone.

Syntax

.local(): FduInstance

Returns

FduInstance - New instance in local time

Examples

Basic Conversion

import { fdu } from "@pyyupsk/fdu";

const utcDate = fdu("2025-10-05T12:00:00Z");
const localDate = utcDate.local();

console.log(localDate.format("YYYY-MM-DD HH:mm"));
// Displays time in your local timezone

UTC to Local Conversion

// Date in UTC
const utcDate = fdu("2025-10-05T14:30:00Z");

// Convert to local time
const localDate = utcDate.local();

// The timestamp remains the same
console.log(utcDate.valueOf() === localDate.valueOf()); // true

// But the displayed time reflects local timezone
console.log(utcDate.format("YYYY-MM-DD HH:mm"));
console.log(localDate.format("YYYY-MM-DD HH:mm"));

Working with API Responses

// API returns UTC timestamp
const apiResponse = await fetch("/api/events");
const data = await apiResponse.json();

// Convert to local time for display
const eventDate = fdu(data.datetime).local();

console.log(`Event: ${eventDate.format("MMMM D, YYYY [at] h:mm A")}`);

Chaining

Since .local() returns a new instance, you can chain it with other operations:

const utcDate = fdu("2025-10-05T12:00:00Z");

const result = utcDate.local().add(1, "day").format("YYYY-MM-DD HH:mm");

Immutability

.local() returns a new instance and never modifies the original:

const original = fdu("2025-10-05T12:00:00Z");
const local = original.local();

// Original remains unchanged
console.log(original.format("YYYY-MM-DD HH:mm"));
// Local shows time in local timezone
console.log(local.format("YYYY-MM-DD HH:mm"));

Common Patterns

Display UTC Times Locally

// Server sends UTC times
const serverTimes = [
  "2025-10-05T08:00:00Z",
  "2025-10-05T14:00:00Z",
  "2025-10-05T20:00:00Z",
];

// Convert all to local time for UI
const localTimes = serverTimes.map((time) =>
  fdu(time).local().format("h:mm A"),
);

console.log(localTimes);
// ['3:00 AM', '9:00 AM', '3:00 PM'] (example for UTC-5)

User Interface Display

const utcTimestamp = fdu("2025-10-05T14:30:00Z");
const userLocal = utcTimestamp.local();

// Display to user in their local timezone
document.getElementById("event-time").textContent = userLocal.format(
  "MMMM D, YYYY [at] h:mm A",
);

Reports and Logs

// Log entries in UTC
const logEntries = [
  { timestamp: "2025-10-05T10:15:00Z", message: "User login" },
  { timestamp: "2025-10-05T10:20:00Z", message: "File uploaded" },
];

// Display in local time for easier reading
logEntries.forEach((entry) => {
  const localTime = fdu(entry.timestamp).local();
  console.log(`[${localTime.format("HH:mm:ss")}] ${entry.message}`);
});

Timezone-Aware Calendar

// Meeting scheduled in UTC
const meeting = fdu("2025-10-05T15:00:00Z");

// Show in user's local timezone
const localMeeting = meeting.local();

console.log(`Meeting: ${localMeeting.format("dddd, MMMM D [at] h:mm A")}`);
// "Sunday, October 5 at 10:00 AM" (example for UTC-5)

Comparing Times Across Timezones

const utcTime = fdu("2025-10-05T12:00:00Z");
const localTime = utcTime.local();

// Same moment in time, different display
console.log(`UTC: ${utcTime.format("YYYY-MM-DD HH:mm")}`);
console.log(`Local: ${localTime.format("YYYY-MM-DD HH:mm")}`);
console.log(`Same timestamp: ${utcTime.valueOf() === localTime.valueOf()}`);
// true - they represent the same moment

Important Notes

.local() preserves the underlying timestamp (.valueOf() remains the same)
The method converts the display to local timezone, not the actual moment in time
Multiple calls to .local() on the same instance return equivalent results
The actual offset depends on your system's timezone settings
Does not handle Daylight Saving Time (DST) transitions—uses current system timezone