Exact, Safe & Reliable TypeScript Utilities
Zero-dependency TypeScript utilities for exact math, financial calculations, safe data handling, locale parsing, dates, security and async workflows.
npm install @fatdevcon/precisekit
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0.1 + 0.2The highlighted digits are floating-point error.
summary(0.1, 0.2)Exact: no digits are lost.
Version 0.3.5 replaced decimal.js and date-fns with an in-package BigInt decimal engine and an ISO 8601 parser and formatter, which removed both runtime dependencies. Supported operations are checked against those libraries as development-only test oracles; this is not a claim of full API or behavioral parity with either. Later releases added features, so the full-package import has grown again while importing a single feature stays small.
Sizes are decimal kilobytes (1 kB = 1,000 bytes). Fixtures and tooling differ between rows, so read the trend rather than small differences.
Named imports from the current release, minified + gzip with the same toolchain. A feature row imports every function in that area; a function row imports one function.
| Import | gzip | Brotli |
|---|---|---|
| Money | 6.1 kB | 5.3 kB |
| Locale parsing | 6.1 kB | 5.2 kB |
| Security | 1.7 kB | 1.5 kB |
| Business calendar | 1.5 kB | 1.3 kB |
| Normalization | 1.8 kB | 1.6 kB |
| Concurrency | 1.2 kB | 1.0 kB |
compactNullish | 0.8 kB | 0.7 kB |
hasByPath | 0.8 kB | 0.7 kB |
pickBy | 1.0 kB | 0.8 kB |
Exact money, locale parsing, safe data normalization, bounded async work, business calendars and security helpers. Import what you need.
Numbers, currencies, percentages, units, compact values and byte sizes through the runtime's Intl data, with ISO 4217 country and currency metadata. Parse sizes and durations back to exact values.
Token-based formatting in any IANA zone, ISO 8601 parsing, calendar arithmetic that respects daylight saving, relative time, and DST-aware offsets in seconds, minutes or hours.
Truncate, mask, slugify and change case without splitting emoji, flags or combining accents. Vietnamese and other diacritics are handled.
Debounce, throttle, memoize, retry with backoff, abort-aware waits and timeouts, plus classic sorting and searching with documented limits.
Every utility is a named export, so imports stay focused. Results below are what the code returns.
import { divide, summary, round } from "@fatdevcon/precisekit";
summary(0.1, 0.2); // 0.3
round(1.005, 2); // 1.01
divide("1", "3", { precision: 5 }); // "0.33333"
summary("100000000000000000000000", "1");
// "100000000000000000000001"import { formatCurrency, formatBytes } from "@fatdevcon/precisekit";
formatCurrency("12345678901234567890.129", "USD");
// "$12,345,678,901,234,567,890.13"
formatCurrency(1234.5, "VND", "vi-VN"); // "1.235 ₫"
formatBytes(1536, { base: 1024 }); // "1.5 KiB"import { formatDate, addMonths } from "@fatdevcon/precisekit";
formatDate(new Date("2026-01-15T17:30:00Z"), "yyyy-MM-dd HH:mm xxx", {
timeZone: "Asia/Ho_Chi_Minh",
}); // "2026-01-16 00:30 +07:00"
formatDate(addMonths("2026-01-31", 1), "yyyy-MM-dd"); // "2026-02-28"import { withRetry } from "@fatdevcon/precisekit";
const config = await withRetry(() => fetch("/config.json").then((r) => r.json()), {
retryCount: 3,
delay: ({ count }) => 200 * 2 ** count,
});Run one supported function call per line against the real package. Values can be strings, numbers, bigints, arrays and objects. Lines are parsed as data and calls, never executed as code.
219 documented functions with parameters, return values, errors and examples. Executable examples are checked against the built package. Illustrative and async examples are marked separately; some environment-dependent expectations are skipped by the docs runner.
The full reference needs JavaScript. See the README overview for workflows; type declarations also ship with the package.
No function matches that filter. Try a shorter word such as format or array.
Short answers to questions developers search for, using only exported APIs.
import { groupBy } from "@fatdevcon/precisekit";
const byRole = groupBy([
{ name: "An", role: "dev" }, { name: "Binh", role: "qa" },
], (user) => user.role);
// { dev: [{ name: "An", ... }], qa: [{ name: "Binh", ... }] }import { sumValueInArray, multiply } from "@fatdevcon/precisekit";
sumValueInArray([19.99, 5.01, 0.1]); // 25.1
multiply("19.99", 3); // "59.97"import { getTimeZoneOffset, formatInTimeZone } from "@fatdevcon/precisekit";
const instant = new Date("2026-01-15T12:00:00Z");
getTimeZoneOffset(instant, "Asia/Ho_Chi_Minh", { unit: "hours" }); // 7
formatInTimeZone(instant, "Asia/Ho_Chi_Minh", "en-GB", {
dateStyle: "short", timeStyle: "short", hourCycle: "h23",
}); // "15/01/2026, 19:00"import { parseBytes, parseDuration } from "@fatdevcon/precisekit";
parseBytes("1.5 GB"); // 1500000000
parseBytes("512 KiB"); // 524288
parseDuration("1h 2m 3s"); // 3723000
parseDuration("2 days, 4 hours"); // 187200000import { setByPath } from "@fatdevcon/precisekit";
const state = { user: { name: "An", tags: ["a"] } };
const next = setByPath(state, "user.tags[1]", "b");
// next.user.tags is ["a", "b"]; state is unchangedimport { formatCurrency } from "@fatdevcon/precisekit";
formatCurrency("12345678901234567890.129", "USD");
// "$12,345,678,901,234,567,890.13"import { compactNullish, pickBy } from "@fatdevcon/precisekit";
compactNullish([0, null, "", undefined, false, 1]); // [0, "", false, 1]
pickBy({ id: 7, note: null, flag: false }, (value) => value !== null);
// { id: 7, flag: false }import { getByPath, hasByPath } from "@fatdevcon/precisekit";
const data = { a: { b: undefined, list: [{ id: 1 }] } };
hasByPath(data, "a.b"); // true
getByPath(data, "a.b"); // undefined
hasByPath(data, "a.list[0].id"); // true
hasByPath(data, "a.missing"); // falseThe full history is in the changelog.
Clean consumer fixtures verify Node, Bun, ESM, CommonJS and strict TypeScript declarations from the packed tarball.
Older changelog and migration records retain the package name under which those versions were released.
Strict conversions, readable ESM/CJS output, exact numeric behavior and zero runtime dependencies remain intact.
The migration from utilities 0.4.2 to PreciseKit 0.5.0 keeps the existing function and type contracts and adds six groups of helpers. Update installation and imports to @fatdevcon/precisekit. See the migration guide.
npm uninstall @fatdevcon/utilities
npm install @fatdevcon/precisekitimport { summary, formatCurrency } from "@fatdevcon/precisekit";The old package is not aliased or deprecated automatically. No function rename or behavioral compatibility break is introduced by the package migration.
Use summary, subtract, multiply, divide and round. They calculate in exact decimal arithmetic, so summary(0.1, 0.2) is 0.3 and round(1.005, 2) is 1.01. Pass bigints or numeric strings when values exceed 2^53.
No. Since 0.3.5 the package has zero runtime dependencies. decimal.js and date-fns are development-only test oracles.
Yes. It ships ESM, CommonJS and type declarations, and public option and result types are exported alongside the functions.
Node.js 18 and newer, Bun, and modern browsers. Formatting and time zone helpers use the standard Intl APIs, so output follows the runtime's locale data.
For many everyday cases, yes: exact arithmetic with rounding modes, ISO parsing, token formatting and common collection helpers are covered. It is a focused toolkit, not a full replacement. Libraries with broader scope, such as complex date arithmetic or arbitrary-base numbers, still fit those jobs better.
It supports a documented subset, including yyyy-MM-dd HH:mm:ss, EEEE, do, xxx and PPpp, and accepts a date-fns locale object as options.locale. It is not a complete date-fns replacement; locale-sensitive output depends on runtime ICU data and the selected locale.
Yes. The package is side-effect free and every utility is a named export, so bundlers drop what you do not import.