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FastjsDate API ​

This page lists every property and method on a FastjsDate instance.

A FastjsDate is the intersection of FastjsDateAtom, FastjsDateAPI and FastjsModuleBase, so methods like setCustomProp, then, setCustomEvent are also available on every instance.

Type Declaration ​

typescript
import type { FastjsDate } from "jsfast";

export interface FastjsDateAtom {
  construct: "FastjsDate";
  format: string;
  _date: number;
  _createAt: number;
  timezoneDiff: number;
}

export interface FastjsDateAPI {
  changeDate(time: number | string): FastjsDate;
  changeFormat(format: string): FastjsDate;
  setZone(zone: number): FastjsDate;
  refresh(): FastjsDate;

  toNumber(utc?: boolean): number;
  toActiveNumber(utc?: boolean): number;

  toString(): string;
  toString(showAs: "utc" | "local" | number): string;
  toString(newFormat: string): string;
  toString(showAs: "utc" | "local" | number, newFormat: string): string;

  toActiveString(): string;
  toActiveString(showAs: "utc" | "local" | number): string;
  toActiveString(newFormat: string): string;
  toActiveString(showAs: "utc" | "local" | number, newFormat: string): string;
}

Properties ​

FastjsDate.format ​

TIP

For the token reference, see Format Table.

Default format used by toString / toActiveString. Mutate it with changeFormat or override per call.

typescript
type format = string;

FastjsDate._date ​

Internal UTC timestamp (milliseconds). Mutate it with changeDate.

typescript
type _date = number;

FastjsDate._createAt ​

Timestamp of the moment the instance was created. Used by toActive* to compute elapsed time. Reset with refresh.

typescript
type _createAt = number;

FastjsDate.timezoneDiff ​

Treat as read-only

Set it with setZone. Touching the field directly is allowed but discouraged.

Stored offset between UTC and the instance's "local" view, expressed in milliseconds. Defaults to the browser's getTimezoneOffset() at construction time.

typescript
type timezoneDiff = number;

Methods ​

FastjsDate.changeDate ​

Replace the stored time. A string is parsed against the current format. Also resets _createAt, so toActive* starts ticking from "now" again.

typescript
date.create().changeDate("2025-01-01 00:00:00");
date.create().changeDate(Date.now());
typescript
changeDate(time: number | string): FastjsDate;

FastjsDate.changeFormat ​

WARNING

Affects every subsequent toString / toActiveString and changeDate(string) call.

typescript
date.create().changeFormat("Y/M/D h:m");
typescript
changeFormat(format: string): FastjsDate;

FastjsDate.setZone ​

Set the offset between UTC and the instance's "local" view, in hours. 8 means UTC+8, 0 means UTC, -5 means UTC-5.

typescript
date.create().setZone(8); // UTC+8
date.create().setZone(0); // UTC
typescript
setZone(zone: number): FastjsDate;

FastjsDate.refresh ​

WARNING

Affects toActiveString / toActiveNumber – they will start counting from "now" again.

Reset _createAt to the current time.

typescript
refresh(): FastjsDate;

FastjsDate.toNumber ​

Return the stored timestamp.

utcReturns
true (default)The raw UTC timestamp
falseThe timestamp shifted by timezoneDiff (i.e. how the instance "looks" locally)
typescript
toNumber(utc?: boolean): number;

FastjsDate.toActiveNumber ​

Same as toNumber, but adds (Date.now() - _createAt) so the value keeps ticking forward. Use it to build clocks or stopwatches that don't drift.

typescript
toActiveNumber(utc?: boolean): number;

FastjsDate.toString ​

Format the stored time as a string. Overloads:

CallBehaviour
toString()Use the default format, render in UTC.
toString("utc")Same as the no-arg form.
toString("local")Apply timezoneDiff first, then format.
toString(8)Treat 8 as a manual UTC+8 offset (hours).
toString("Y/M/D")Override the format string only.
toString("local", "Y/M/D")Combine timezone + override format.
typescript
const d = date.create();
d.toString(); // UTC
d.toString("local"); // browser timezone
d.toString(8); // UTC+8
d.toString("Y/M/D h:m"); // custom format, UTC
d.toString("local", "Y/M/D"); // custom format + local timezone

Type Declaration ​

typescript
toString(): string;
toString(showAs: "utc" | "local" | number): string;
toString(newFormat: string): string;
toString(showAs: "utc" | "local" | number, newFormat: string): string;

FastjsDate.toActiveString ​

Same overloads as toString, but the underlying time is toActiveNumber() instead of toNumber(), so the result moves forward in real time.

TIP

See Convert to string for a worked example (clock + stopwatch).

Type Declaration ​

typescript
toActiveString(): string;
toActiveString(showAs: "utc" | "local" | number): string;
toActiveString(newFormat: string): string;
toActiveString(showAs: "utc" | "local" | number, newFormat: string): string;