duckkit update — validate, encode, and new object utils 🦆

quick update on what I shipped this week in duckkit.

if you haven't seen it before — duckkit is a TypeScript utility library. zero dependencies, tree-shakeable, everything properly typed. the kind of helpers you keep rewriting in every project.

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what's new

validate module

the one I kept putting off. finally wrote it properly.

import { isEmail, isUrl, isUUID, isIP, isCreditCard, isPhone } from 'duckkit/validate'
import { isString, isNumber, isObject, isNullOrUndefined, isEnum } from 'duckkit/validate'

the type guards actually narrow the type:

function process(value: unknown) {
  if (isString(value)) {
    value.toUpperCase()  // TypeScript knows it's a string ✅
  }
}

isNaN and isFinite fix the native JS gotchas:

// native — broken
isNaN('hello')    // true 😬
isFinite('42')    // true 😬

// duckkit — uses Number.isNaN / Number.isFinite
isNaN('hello')    // false ✅
isFinite('42')    // false ✅

isEnum checks values, not keys:

enum Direction { Up = 'UP', Down = 'DOWN' }

isEnum('UP', Direction)   // true ✅
isEnum('Up', Direction)   // false — 'Up' is a key, not a value
isEnum('LEFT', Direction) // false

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encode module

import { encodeBase64, decodeBase64, encodeHex, decodeHex, encodeUri, decodeUri, encodeJson, decodeJson } from 'duckkit/encode'

all decode functions return null on failure instead of throwing:

decodeBase64('!!!invalid')  // null — no try/catch needed ✅
decodeJson('not json')      // null ✅
decodeUri('%zz')            // null ✅

Base64URL for tokens and URLs — no +, /, or =:

encodeBase64Url('hello world')  // "aGVsbG8gd29ybGQ" — safe in URLs ✅

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new object functions

deepFreeze — returns DeepReadonly<T>, mutations caught at compile time:

const config = deepFreeze({ db: { host: 'localhost', port: 5432 } })
config.db.port = 9999  // TypeScript error ❌

objectDiff — what changed between two objects:

objectDiff({ a: 1, b: 2 }, { a: 1, b: 3, c: 4 })
// ['b', 'c'] — b changed, c was added

mergeIf — merge but skip null/undefined values:

mergeIf({ name: 'Zura', role: 'admin' }, { role: undefined, age: 25 })
// { name: 'Zura', role: 'admin', age: 25 } — role preserved ✅

hasOwn — safe typed Object.hasOwn:

const obj = { hasOwnProperty: () => false, a: 1 }
obj.hasOwnProperty('a')  // false ❌ — overridden
hasOwn(obj, 'a')         // true  ✅ — safe

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install

npm install duckkit

npm · GitHub · Docs

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what utility do you keep rewriting that should be in here? 👇