dietrichgebert--ponytail/docs/platform-native.md

Platform-Native Solutions

The lazy senior dev's first question is always: does the platform already do this?

This document answers that question for the most common cases. Before reaching for a package, scan here. The platform ships with your app for free, doesn't break on updates, and was written by people whose job is exactly that problem.

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HTML Elements

Things the browser already has as a form control.

You think you need	What the platform has
Date picker library	<input type="date">
Time picker library	<input type="time">
Color picker library	<input type="color">
Range slider library	<input type="range">
Progress bar component	<progress value="70" max="100">
Meter/gauge component	<meter value="0.7">
Modal/dialog library	<dialog> + dialog.showModal()
Accordion/FAQ component	<details><summary>Title</summary>…</details>
Tooltip library	title attribute + CSS ::before/::after
Searchable dropdown	<input list="id"> <datalist id="id">
Auto-growing textarea	field-sizing: content (CSS)
Sticky header	position: sticky; top: 0 (CSS)

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CSS Capabilities

Things developers reach for JavaScript to do.

You think you need JS for	What CSS has
Responsive font size	font-size: clamp(1rem, 2.5vw, 2rem)
Fluid spacing	padding: clamp(1rem, 5vw, 3rem)
Dark mode	@media (prefers-color-scheme: dark)
Reduced motion	@media (prefers-reduced-motion: reduce)
Responsive layout without breakpoints	grid-template-columns: repeat(auto-fill, minmax(250px, 1fr))
Component-level responsive design	@container queries
Global design tokens / theming	CSS custom properties (--color-primary: #7c3aed)
Smooth scroll	scroll-behavior: smooth
Scroll-snap carousel	scroll-snap-type: x mandatory + scroll-snap-align: start
Aspect ratio enforcement	aspect-ratio: 16 / 9
Truncate text with ellipsis	overflow: hidden; text-overflow: ellipsis; white-space: nowrap
Multi-line text clamp	-webkit-line-clamp: 3
CSS cascade layers (style isolation)	@layer base, components, utilities
Nested CSS selectors	Native CSS nesting (no preprocessor needed)
has() parent selector	:has(input:checked)

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JavaScript / Browser APIs

Libraries people install that the runtime already ships.

You think you need	What the platform has
query-string / qs	new URLSearchParams(location.search)
lodash.clonedeep	structuredClone(obj)
lodash.groupby	Object.groupBy(arr, fn)
lodash.debounce	see debounce one-liner below
numeral / accounting	new Intl.NumberFormat("en-US", { style: "currency", currency: "USD" })
date-fns format	new Intl.DateTimeFormat("en-US", { dateStyle: "long" }).format(date)
date-fns relative time	new Intl.RelativeTimeFormat("en", { numeric: "auto" }).format(-3, "day")
plural / i18n plurals	new Intl.PluralRules("en-US").select(count)
clipboard.js	navigator.clipboard.writeText(text)
uuid (v4)	crypto.randomUUID()
Infinite scroll library	new IntersectionObserver(cb).observe(sentinel)
Resize listener library	new ResizeObserver(cb).observe(element)
DOM mutation watcher	new MutationObserver(cb).observe(el, options)
uuid-validate	/^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$/i.test(id)
is-online / connectivity check	navigator.onLine + online/offline events
sharesheet library	navigator.share({ title, text, url })
store.js / localForage (simple case)	localStorage.setItem(key, JSON.stringify(val))
Abort fetch on timeout	AbortSignal.timeout(5000) passed to fetch
Custom event bus	new EventTarget() / dispatchEvent(new CustomEvent("x", { detail }))

Debounce one-liner (no library):

// ponytail: 3 lines beats a dependency
let t;
const debounce = (fn, ms) => (...args) => { clearTimeout(t); t = setTimeout(() => fn(...args), ms); };

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Swift / SwiftUI

UI components people reach for a library or a custom view for.

You think you need	What the platform has
Date/time picker library	DatePicker
Color picker library	ColorPicker
Search bar + filtering	.searchable(text:)
Pull-to-refresh library	.refreshable { }
Swipe-to-delete / row actions	.swipeActions { }
Async image loading + cache	AsyncImage
Charting library	Swift Charts (import Charts)
Markdown rendering	Text(...) markdown / AttributedString(markdown:)
Share sheet wrapper	ShareLink
Loading spinner	ProgressView()
Photo picker	PhotosPicker
Map SDK (basic)	Map (MapKit for SwiftUI)
Grid layout library	Grid / LazyVGrid

Frameworks and stdlib that wrappers wrap.

You think you need	What the platform has
JSON library (SwiftyJSON)	Codable + JSONDecoder / JSONEncoder
HTTP client (Alamofire, simple use)	URLSession async/await; Alamofire earns it for complex retry/multipart at scale
Date/number/currency formatting	.formatted() / FormatStyle
Regex library	Swift regex literals + Regex
Crypto library (CryptoSwift)	CryptoKit
Keychain wrapper	Security SecItem; a few lines, not a dependency
Persistence / ORM	SwiftData, or @AppStorage for small key-values
Logging library	Logger (os.log)
UUID / Base64 helpers	UUID(), Data(...).base64EncodedString()
Image downsampling	ImageIO CGImageSourceCreateThumbnailAtIndex
Combine wrappers for async	async/await + AsyncSequence

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Node.js Standard Library

Packages that wrap Node built-ins.

You think you need	What Node has
mkdirp	fs.mkdirSync(path, { recursive: true })
rimraf	fs.rmSync(path, { recursive: true, force: true })
make-dir	fs.mkdirSync(path, { recursive: true })
slash (win paths)	path.posix or path.normalize()
uuid (v4)	crypto.randomUUID()
ms (parse duration strings)	keep ms, it's genuinely useful and tiny
is-stream	val instanceof stream.Readable
object-assign	Object.assign() / spread
array-uniq	[...new Set(arr)]
array-flatten	arr.flat(Infinity)
flat	arr.flat(depth)
path-exists	fs.existsSync(path)
load-json-file	JSON.parse(fs.readFileSync(path, "utf8"))
write-json-file	fs.writeFileSync(path, JSON.stringify(obj, null, 2))
pkg-dir	path.resolve(__dirname, "..") / import.meta.dirname

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Python Standard Library

Packages that wrap what Python already ships.

You think you need	What Python has
python-dateutil (basic parsing)	datetime.fromisoformat() (Python 3.7+)
pytz	zoneinfo.ZoneInfo("America/New_York") (Python 3.9+)
attrs (simple data classes)	@dataclass
six	drop it, Python 2 is gone
pathlib2	pathlib.Path (built-in since Python 3.4)
enum34	enum.Enum (built-in since Python 3.4)
typing_extensions (common types)	from __future__ import annotations + built-in generics
simplejson (basic use)	json (stdlib)
requests (simple GET)	urllib.request.urlopen(url), requests for anything real
click (single command)	argparse (stdlib)
mergedeep	dict | other_dict (Python 3.9+)
more-itertools (basic)	itertools (stdlib): chain, islice, groupby, product
toolz (basic)	functools: lru_cache, partial, reduce
tabulate (dev/debug only)	pprint.pprint() for quick inspection

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Database

Things the application layer implements that the database already does.

You think you need app code for	What the database has
Pagination offset/limit	LIMIT 20 OFFSET 40
Running totals	SUM(...) OVER (ORDER BY date) (window function)
Rank within group	RANK() OVER (PARTITION BY category ORDER BY score DESC)
Pivot / cross-tab	FILTER (WHERE ...) + conditional aggregation
Deduplication	SELECT DISTINCT / ON CONFLICT DO NOTHING
Soft-delete filtering	Generated column + partial index
Tree traversal	Recursive CTE (WITH RECURSIVE)
Full-text search (basic)	tsvector / MATCH AGAINST / FTS5
JSON storage + query	jsonb (Postgres) / JSON_EXTRACT (SQLite/MySQL)
UUID generation	gen_random_uuid() (Postgres) / UUID() (MySQL)
Timestamps on insert/update	DEFAULT now() + trigger or ON UPDATE CURRENT_TIMESTAMP
Enforce uniqueness	UNIQUE constraint, not application-level checks
Enforce referential integrity	FOREIGN KEY, not application-level checks
Enforce value ranges	CHECK (price > 0), not application-level validation

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The Pattern

Across every layer, the pattern is the same:

Platform team spends years solving the problem.
Package author wraps it.
You install the wrapper.
The wrapper goes unmaintained.
You debug the wrapper.

Skip the wrapper. The platform ships with your app for free.

When the native solution is genuinely insufficient (old browser support, edge cases it doesn't handle, ergonomics that matter at scale), the library earns its place. Install it then, not before.