Rust

flat_map and Iterator::flatten

`flat_map(f)` is `map(f).flatten()` — map each item to an iterator, then concatenate. Indispensable for working with nested structures.

46m ago 0

Go

Test Helpers with t.Helper()

When you extract a verification routine into a helper, call `t.Helper()` so failure messages point to the CALLER line — not the helper line. One line, much better diagnostics.

46m ago 0

Java

flatMap — Flatten Nested Streams

Map each element to a Stream, then concatenate all of them into one. Used everywhere from "all words from a list of sentences" to "all permissions from a list of roles".

46m ago 0

SQL

COALESCE / NULLIF — Null Handling

`COALESCE(a, b, c)` returns the first non-NULL value — perfect for fallbacks. `NULLIF(a, b)` returns NULL when a equals b — handy for "treat sentinel as null".

46m ago 0

PHP

Validate Password Strength

Score a password 0–4 (NIST-inspired, not the full zxcvbn algorithm). Encourages length over complexity; flags well-known weak patterns. Use as a UI hint, not a hard barrier.

46m ago 0

HTML

All Standard Input Types

HTML5 input types each have built-in validation, on-screen keyboards (mobile), and pickers. Use them — `<input type="number">` beats `<input type="text">` + JS validation every time.

46m ago 0

HTML

Card Pattern (article + link wrapper)

The standard content card — image, title, excerpt, meta. Make the WHOLE card clickable by wrapping the title link and using `::after` to extend the hit area to the full card.

46m ago 0

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`).

46m ago 0

JavaScript

Flatten Nested Array

Recursively flattens an array of arbitrary nesting depth into a single flat array. Accepts an optional depth limit — pass Infinity to flatten completely. Uses the native Array.flat when the browser supports it, otherwise falls back to a recursive reduce.

46m ago 0

TypeScript

Sleep / Delay

The async/await-friendly version of `setTimeout`. The one-liner everyone re-invents — keep it in a util file. Optional AbortSignal lets you cancel mid-wait.

46m ago 0

TypeScript

range — Lazy Number Iterator

A generator-based numeric range: `[start, end)` with an optional step. Lazy so it doesn't allocate a huge array up front; consume with for…of or Array.from.

46m ago 0

Rust

tokio mpsc Channel

Async multi-producer / single-consumer channel. Producers `.send()`, the single receiver `.recv().await` items as they arrive. Bounded — the channel back-pressures producers when full.

46m ago 0

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).

46m ago 0

Kotlin

Write to a File

`writeText` overwrites; `appendText` appends. For multiple writes, use `bufferedWriter().use { }` for efficiency + auto-close.

46m ago 0

HTML

Code Markup — pre, code, kbd, samp, var

HTML has five semantic elements for technical text: `<code>` (source code), `<pre>` (preserve whitespace), `<kbd>` (keyboard input), `<samp>` (sample output), `<var>` (math/program variable). Each has a different meaning to screen readers and search engines.

46m ago 0

Kotlin

Ktor Server — Middleware (Plugins)

Plugins wrap every request — logging, CORS, auth, rate limiting. Install with `install(Plugin) { config }` at the application level.

46m ago 0

Java

Jackson — Basic ObjectMapper

`com.fasterxml.jackson.databind.ObjectMapper` is the JSON standard for Java. Construct once (it's expensive + thread-safe) and reuse for every serialization in your app.

46m ago 0

PHP

Validate URL (scheme + host)

Beyond filter_var, also require the URL to have an http(s) scheme and a non-empty host. Rejects "javascript:" and other risky pseudo-schemes commonly seen in stored XSS.

47m ago 0

Rust

Threads with thread::spawn + join

Native OS threads with `std::thread::spawn`. The returned `JoinHandle` lets you wait for the thread and get its return value. Use `move` to transfer ownership of captured variables.

47m ago 0

Bash

Process Substitution Cheatsheet

`<(...)` makes a command's output look like a file; `>(...)` makes a command's input look like a file. Killer feature for tools that only accept filenames.

47m ago 0

Go

errgroup — Fan-Out with Cancellation

`golang.org/x/sync/errgroup` runs N goroutines, returns the first error, and cancels the others via a shared context. The right pattern for parallel I/O where any failure should abort the rest.

47m ago 0

HTML

Semantic Article Structure

`<article>` for self-contained content (blog post, comment, news item). Each article gets its own header, body, and (optionally) footer. Helps screen readers, RSS, and Google understand structure.

47m ago 0

JavaScript

DOM Ready Helper

Runs a callback when the DOM is fully parsed and ready, without waiting for images or stylesheets. Works whether called before or after DOMContentLoaded has already fired — unlike a bare addEventListener which misses the event if the DOM is already ready when the script runs.

47m ago 0

PHP

Detect & Strip Byte Order Mark

Some text editors prepend a UTF-8 BOM (0xEF 0xBB 0xBF) which breaks header() calls, JSON, and PHP output. Detect and strip it defensively when ingesting external files.

47m ago 0

Rust

zip / enumerate / chain

Three adapters that pair, index, and concatenate iterators. Every Rust developer reaches for them daily.

47m ago 0

SQL

date_trunc — Bucket Times into Hours/Days/Weeks

`date_trunc('day', ts)` rounds a timestamp down to the start of the day. Use for time-series GROUP BYs — daily/weekly/hourly buckets without messy arithmetic.

47m ago 0

Python

JWT Sign + Verify (PyJWT)

The de-facto JWT library for Python. HS256 demo with an exp claim and the standard "verify everything" decode flow. Mind that PyJWT raises specific exceptions you can catch separately.

47m ago 0

Java

CountDownLatch — Wait for N Events

Block one or more threads until a count of events occurs. Set the count up front; each event calls `countDown()`; waiters call `await()`. Classic "wait until all workers are ready" pattern.

47m ago 0

Java

Generic Class with Type Parameter

Stamp out type-safe containers and helpers — same class body, multiple element types. The `<T>` declaration is what makes it generic.

47m ago 0

PHP

Word Count (UTF-8 aware)

Count words in a string in a way that works for any Unicode script — including those without ASCII whitespace. Built on the \p{L}\p{N} Unicode regex categories.

47m ago 0