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JavaScript Flatten Object (Dot Notation)
Flattens a deeply nested object into a single-level object with dot-notation keys. Useful for comparing configs, building form field names from nested data, logging structured objects to analytics, or preparing data for flat key-value stores like Redis or environment variables.
JavaScript Cookie Helpers (Get / Set / Delete)
Minimal cookie utilities: getCookie retrieves a value by name, setCookie writes a cookie with optional expiry days and path, deleteCookie removes it by setting an expired date. No library needed for simple first-party cookie management. For complex scenarios (SameSite, Secure, partitioned) extend the options object.
JavaScript Middleware Pipeline
A simple Koa/Express-style middleware runner for client-side use. Middleware functions receive a context object and a next() function — call next() to pass control to the next middleware or skip it to short-circuit the chain. Useful for building plugin systems, request pipelines, and composable validation logic.
JavaScript i18n Minimal Translator
A tiny internationalisation helper that loads a locale dictionary and resolves translation strings by dot-notation key. Supports variable interpolation via {{placeholder}} syntax. Falls back to the key itself when a translation is missing, keeping the UI readable during development. Swap the locale at runtime without a page reload.
JavaScript Serialize Form to Object
Converts all named form fields into a plain JavaScript object using the FormData API. Handles text inputs, selects, textareas, and checkboxes. Multiple values for the same name (e.g. multi-select, checkboxes) are collected into an array. Ready to JSON.stringify and POST to an API.
Kotlin map / filter / reduce
The three classic functional combinators. Each takes a lambda and returns a new collection (or a single value for reduce). Chain freely — intermediate allocations only matter at very large scale (use `Sequence` then).
TypeScript takeWhile / dropWhile
Consume or skip leading elements as long as a predicate holds. Useful for parsing prefixed sequences (e.g. all leading whitespace tokens, all unread notifications, etc.).
Kotlin Sequences — Lazy Collections
A `List` materializes every intermediate `map`/`filter` result. A `Sequence` processes ONE element through the whole pipeline at a time — better for big inputs or short-circuiting (`first`, `take`).
JavaScript Chunk Array
Splits an array into smaller arrays (chunks) of a specified size. The last chunk may be smaller if the array length is not evenly divisible. Useful for batch processing, pagination, rendering large lists in chunks, and rate-limited API calls.
Kotlin Custom Exception + Sealed Result Pattern
For library / service code, define your own exception hierarchy. Pair with `sealed` + `when` for type-safe error handling at the call site.
Kotlin StateFlow — Observable State
`StateFlow<T>` is a hot Flow holding a single current value. Perfect for UI state in Compose/Android — always has a value, conflates intermediate values, multi-subscriber.
Kotlin kotlin.time — Duration and measureTime
`kotlin.time.Duration` is a typesafe time amount with friendly literal syntax (`5.seconds`, `2.minutes`). `measureTime { }` benchmarks a block.
Kotlin fold and scan
`fold` accumulates from a seed across all items. `runningFold` / `scan` yields every intermediate accumulator value — running totals, cumulative metrics.
Kotlin Enums with Properties and Methods
Kotlin enums can carry constructor properties and define methods — including abstract methods overridden per constant. Way more expressive than Java enums.
Kotlin groupBy and partition
`groupBy` returns a `Map<Key, List<T>>` keyed by what the lambda returns. `partition` is a special-case `groupBy` for booleans — returns `(matching, nonMatching)` Pair.
Kotlin ViewModel + StateFlow + Compose
Standard Android pattern: ViewModel holds state in a `StateFlow`, Compose collects it as state. Survives config changes; isolates business logic from UI.
Kotlin Sealed Interfaces (Kotlin 1.5+)
Like sealed classes, but for interfaces — and a class can implement multiple sealed interfaces. Cleaner state modeling when you want "this is both a Loadable and a Cacheable".
PHP Build & Sign a JWT (HS256)
Generate a JWT manually using only base64-url and hash_hmac — no library required. Demonstrates header/payload/signature concatenation and the exp claim.