Tempo Cookbook

A collection of recipes for solving common date and time challenges using Tempo.

Table of Contents

1. The Basics
2. Parsing Challenges
3. Manipulation and Calculations
4. Timezones and Locales
5. Business Logic and Terms
6. Formatting and Localization
7. Interoperability

---

The Basics

How do I get the current date and time?

By default, the constructor returns "now".

const now = new Tempo();
console.log(now.toString());

Get "Now" in UTC

const utcNow = new Tempo({ timeZone: 'UTC' });

How do I format a date for my UI?

Use the placeholder syntax in the .format() method.

const t = new Tempo('2024-12-25');
t.format('{dd} {mon} {yyyy}');  // "25 December 2024"
t.format('{h12}:{mi}');         // "12:00am"

How do I check if a date is valid?

const t = new Tempo('invalid-date');
if (t.isValid) {
  // ...
}

Global Configuration

You can initialize global defaults that apply to all future Tempo instances.

Tempo.init({
  timeZone: 'UTC',
  locale: 'en-GB',
  silent: true
});

👉 Learn More: Configuration Guide

---

Parsing Challenges

Parsing "Ambiguous" Digits (US vs UK)

Tempo intelligently resolves ambiguous dates like 04012026 based on your timezone.

const us = new Tempo('04012026', { timeZone: 'America/New_York' }); 
console.log(us.format('{mon} {dd}')); // "April 01"

👉 Learn More: Ambiguity Resolution Guide

Handling Relative Strings

Tempo natively understands human-readable offsets.

new Tempo('yesterday');
new Tempo('next Friday');
new Tempo('2 weeks ago');
new Tempo('tomorrow afternoon');

👉 Learn More: You can seamlessly localize relative phrases (e.g. next to prochain) by reading the Internationalized Parsing Guide.

Parsing Unix Timestamps

Tempo handles both milliseconds (Number) and nanoseconds (BigInt).

new Tempo(1716163200000);         // Milliseconds
new Tempo(1716163200000000000n);  // Nanoseconds

---

Manipulation and Calculations

Add or Subtract Time

Tempo instances are immutable; add() returns a new instance.

const deadline = new Tempo().add({ days: 7, hours: 2 });
const past = new Tempo().add({ months: -1 });

// You can also step by semantic Terms using the `#` prefix!
const t1 = new Tempo('2024-05-15'); // Middle of Q2
const t2 = t1.add({ '#quarter': 1 }); // Middle of Q3: "2024-08-14" (approx)

Jumping to Boundaries (start, mid, end)

The .set() method allows you to jump to the boundaries of native units (like months or years) or semantic Terms (using the # prefix). You can specify whether to land on the inclusive start, inclusive end, or the exact center.

// Native Units
const monthStart = new Tempo().set({ start: 'month' });

// Semantic Terms (Lands on 30-Sep 23:59:59.999... Inclusive End)
const qtrEnd = new Tempo().set({ end: '#quarter' });

// Lands on the arithmetic nanosecond midpoint of the period
const qtrMid = new Tempo().set({ mid: '#quarter' });

Slick Object Mutations

You can navigate relative to your current date by using Slick Shorthand operators directly inside .set(). Use the snippet shorthand keys (yy, mm, ww, dd, wkd, etc.) and provide a string payload containing a directional modifier:

const t = new Tempo('2024-05-20'); // Monday
t.set({ mm: '>2' });               // July 20th
t.set({ wkd: '>Fri' });            // May 24th

👉 Learn More: To read about advanced chaining, order-of-operations, and architectural limitations, see the Slick Object Mutations Deep Dive.

How long until a deadline? (until)

const t = new Tempo();
const daysLeft = t.until('2025-01-01', 'days');
console.log(`${daysLeft} days remaining`);

Relative Time (since)

Generate human-readable relative time strings instantly.

const t = new Tempo('yesterday');
console.log(t.since()); // "1d ago"

---

Timezones and Locales

Convert Time to Another Zone

const nyc = new Tempo('2024-05-20 10:00', { timeZone: 'America/New_York' });
const london = nyc.set({ timeZone: 'Europe/London' });

console.log(nyc.format('{hh}:{mi}'));    // "10:00"
console.log(london.format('{hh}:{mi}')); // "15:00"

---

Business Logic and Terms

Is it the weekend?

const t = new Tempo();
const isWeekend = t.dow >= 6; // Saturday = 6, Sunday = 7

What Fiscal Quarter are we in?

Using the qtr Term plugin (term.qtr is a convenient alias for the full term.quarter property).

const t = new Tempo();
console.log(`Current Quarter: ${t.term.qtr}`); // "Q1", "Q2", etc.

Hemispheric Seasons

Tempo Terms are hemisphere-aware.

const sydney = new Tempo('2024-07-01', { sphere: 'south' });
console.log(sydney.term.szn); // "Winter"

const london = new Tempo('2024-07-01', { sphere: 'north' });
console.log(london.term.szn); // "Summer"

// or even via the timeZone setting
console.log(new Tempo({ timeZone: 'America/New_York' }).term.szn); // "Summer"
console.log(new Tempo({ timeZone: 'Australia/Sydney' }).term.szn); // "Winter"

---

Formatting and Localization

Semantic Formatting

Use specific Term tokens like {#quarter} or {#season} to automatically embed a Term's label (or key) into a format string.

const t = new Tempo();
console.log(t.format('We are currently in the {#quarter}')); // "We are currently in the First Quarter"

Format Modifiers & Localization

Format strings support chained colon-modifiers (e.g., :upper, :locale, :ord) to dynamically change the presentation casing or delegate to the native Intl API. You can stack them to get the exact presentation required!

const t = new Tempo('2024-05-15 15:30', { locale: 'fr-FR' });

t.format('{mon:upper}');             // "MAY" (English Default -> UpperCase)
t.format('{mon:long}');              // "mai" (Native French Intl output via styling bridge)
t.format('{mon:long:upper} {dd}');   // "MAI 15" (Native French Intl output)

👉 Learn More: See the Smart Formatting Guide for the complete list of available modifiers.

TIP

Tired of typing styling modifiers?
If you find yourself repeatedly writing :long or :short for the same localized date structure, save it to the global FORMATS registry! This creates a clean, reusable shortcut:

Tempo.init({
    locale: 'fr-FR',
    registry: {
        formats: {
            'ui-date': '{wkd:long}, {dd:raw} {mon:long} {yyyy}'
        }
    }
});

t.format('ui-date'); // Resolved with all modifiers intact!

Note: Format keys are resolved case-sensitively from the global registry.formats object. If the requested key is not found, Tempo will simply treat the provided string as a literal layout string rather than throwing an error.

👉 Learn More: To build custom zero-overhead logic evaluators (like Fiscal Years or native Intl bridges), read the Custom Format Tokens Deep Dive.

👉 Learn More:

• Smart Formatting Guide
• The Role of Locale
• Smart Parsing Guide

---

Ticker Plugin

The Ticker engine is a premium plugin for precisely driving business logic (like recurring billing or reporting cycles) on specific date boundaries.

// Drive internal reporting precisely when a new quarter begins
await using quarterly = Tempo.ticker({ '#quarter': 1 });

for await (const t of quarterly) {
  generateReport(t.term.qtr);
}

👉 Learn More: See the Ticker Plugin Documentation for detailed configuration, term-driven intervals, and await using syntax requirements.

---

Interoperability

Converting to / from Native Date

const date = new Tempo().toDate();
const tempo = new Tempo(new Date());

Converting to Temporal Objects

const zdt = new Tempo().toDateTime();  // Temporal.ZonedDateTime
const instant = new Tempo().toInstant(); // Temporal.Instant
const pdt = new Tempo().toPlainDate(); // Temporal.PlainDate

Sorting an array of Tempos

const dates = [new Tempo('tomorrow'), new Tempo('yesterday'), new Tempo('today')];
dates.sort(Tempo.compare); // Sorts chronologically