Why Doran

Doran's core is a zero-dependency, immutable, tree-shakeable Jalali engine with IANA time zones built in. Against the usual stack — moment + moment-jalaali — that translates into a much smaller bundle and faster hot paths, with no second library for time zones.

Bundle size

Measured with the same pipeline (esbuild --minify, then gzip) so the numbers are comparable — not pulled from different sources.

Setup	Minified	Gzipped
moment + moment-jalaali	85.5 kB	25.1 kB
dayjs + jalaliday	16.0 kB	6.2 kB
@doranjs/core (full barrel)	23.5 kB	7.9 kB
@doranjs/core — DoranDate + format	19.1 kB	6.3 kB
@doranjs/core — conversion primitives only	4.6 kB	1.8 kB
@doranjs/core — Duration only	5.3 kB	1.8 kB

Doran is roughly 3× smaller gzipped than moment + moment-jalaali — a real migration dropped ~63 kB from an app bundle by removing moment. It is in the same class as dayjs + a Jalali plugin, but zero-dependency, with IANA time zones built in (no moment-timezone), immutable, and Jalali as a first-class calendar rather than a plugin.

Tree-shaking

@doranjs/core is "sideEffects": false and fully ESM, so bundlers drop what you don't import. Pull only what you use:

// Just the calendar math — ~1.8 kB gzipped, no formatter, no parser.
import { jalaliToGregorian, gregorianToJalali } from '@doranjs/core';

Import named exports (not import * as), and let your bundler do the rest.

Performance

Operations per second, higher is better. @doranjs/core vs moment + moment-jalaali, Node 20, both pinned to a fixed time zone for a fair comparison (moment-jalaali is not time-zone-aware by default).

Operation	@doranjs/core	moment + moment-jalaali	Speedup
format	~315,000	~289,000	1.1×
parse	~210,000	~128,000	1.7×
construct	~250,000	~127,000	2.0×
diff (days)	~38,000,000	~2,200,000	17×

Reproduce locally:

pnpm --filter @doranjs/core build
node packages/core/bench/index.mjs

Reuse the time zone

Constructing with an explicit { timeZone } (or the system default once) lets Doran cache the underlying Intl.DateTimeFormat. Re-resolving the system zone on every call is the one thing that measurably slows construction down.

Beyond the numbers

• Zero runtime dependencies — nothing to audit or get a CVE from.
• Time zones built in — DST-correct IANA conversion without a second package.
• Immutable — every operation returns a new instance; no accidental mutation.
• One instant, two calendars — toISOString() for your backend, format() for Jalali display. See Backends & serialization.
• TypeScript-native, with a familiar dayjs/moment token vocabulary.

CI guards the published bundle with a gzip budget (scripts/size-check.mjs), so these numbers stay honest as the library grows.