@gj-kit/format recipes

Each code block reuses a public-contract example already type-checked in the package README.

1. Format a timestamp with an explicit timezone

Keep timezone and separator beside the display call so screens cannot inherit different defaults.

Outcome: A stable display label whose timezone and separator are explicit at the call site.

Application-owned boundary: Choose the timezone and separator in code; do not let persisted or operational values inherit device defaults.

import { formatDateTime } from '@gj-kit/format';

export const dateLabel = formatDateTime(Date.UTC(2026, 7, 26, 0, 0), {
  timeZone: 'Asia/Seoul',
  separator: '-',
});

2. Format money and bytes without hidden meaning

Select currency and zero-value behavior in code rather than allowing a formatter to guess policy.

Both @ts-expect-error lines hold against the published dist/index.d.ts under strict + exactOptionalPropertyTypes, and fallback: null widens the return type to exactly string | null.

import { formatBytes, formatDateTime, parseIsoInstant } from '@gj-kit/format';

declare const createdAt: string; // app-owned: an ISO string straight off the API

// @ts-expect-error 'GB' labels a decimal divisor, but 'binary' divides by 1024.
formatBytes(1, { system: 'binary', maxUnit: 'GB', unitSpace: true, nonPositive: 'render' });

// @ts-expect-error a wall-clock string never reaches a formatter — parse it first.
formatDateTime(createdAt, { timeZone: 'Asia/Seoul', separator: '-' });

const instant = parseIsoInstant(createdAt, { assumeNoOffset: 'utc' });

export const stamp: string = formatDateTime(instant, { timeZone: 'Asia/Seoul', separator: '-' });

// fallback widens the return type by exactly what you passed, and nothing more.
export const sizeChip: string | null = formatBytes(0, {
  system: 'decimal', unitSpace: false, nonPositive: 'fallback', fallback: null,
});

Use the complete API reference for every export and import path.