TypeScript

usePrevious — Track Last Render's Value

Returns the value the prop/state had on the previous render. Useful for detecting transitions (e.g. "the count just went from 0 to 1") inside effects.

7h ago 0

Bash

ANSI Color Output Helpers

Wrap printf with ANSI escape codes for color and bold. Auto-disable if stdout isn't a TTY (so piping to a file doesn't pollute it with escape sequences).

7h ago 0

Rust

Newtype Pattern (zero-cost wrappers)

Wrap a primitive in a tuple struct to give it a distinct type identity at the type level — without runtime cost. Replaces "is this number a UserId or a PostId?" bugs.

7h ago 0

Go

filepath.Walk — Recursive Tree Walk

`filepath.WalkDir` (Go 1.16+) is the modern, faster version. Visit every file/dir under a root; the callback decides whether to skip or process.

7h ago 0

SQL

WITH Clause — Common Table Expressions

Name a subquery so you can refer to it like a table. Improves readability for complex multi-stage queries — and lets you reuse the same logical block multiple times.

7h ago 0

HTML

Accessible Data Table

Real tables need `<caption>`, `<thead>` / `<tbody>` / `<tfoot>`, and `<th scope="col">` headers. Screen readers use these to announce column/row context on every cell.

7h ago 0

Kotlin

JSON Annotations — Rename, Default, Optional

Per-field annotations let you map Kotlin camelCase ↔ JSON snake_case, set defaults for missing fields, and skip nulls.

7h ago 0

Kotlin

Type-Safe Builder DSL

`@DslMarker` + lambdas with receivers let you build statically-typed DSLs that look like declarative configuration. The HTML / Gradle Kotlin DSL style.

7h ago 0

Kotlin

tailrec — Tail-Call Optimization

Mark a recursive function `tailrec` and the compiler rewrites it as a loop — no stack frame per call, no StackOverflowError on deep recursion. Function must end with itself as the FINAL expression.

7h ago 0

PHP

Dump Variable to Browser (var_dump replacement)

A nicer var_dump-style dumper that wraps output in <pre> with monospaced font for browser inspection. Drop-in replacement for var_dump while debugging.

7h ago 0

TypeScript

Type-Safe Event Emitter

A 30-line type-safe mini EventEmitter. The event-name → payload map is enforced at compile time, so emit and on calls can't drift apart.

7h ago 0

Python

Walk Directory Tree (Filtered)

Recursively yield every file under a directory matching a predicate. Built on pathlib.rglob; the predicate gives you precise control without listing the whole tree up front.

7h ago 0

Bash

Clean Up Merged Branches

Delete every local branch that's been merged to main. Filters out main/master and the current branch as a safety net.

7h ago 0

TypeScript

Conditional Types Basics

`T extends U ? X : Y` lets types branch on shape. Combine with `infer` to extract pieces of complex types — the building block under `ReturnType`, `Parameters`, and most utility libraries.

7h ago 0

Bash

Sort an Array

Bash itself doesn't sort arrays — you pipe through `sort`. readarray captures the sorted output back into an array, preserving each element verbatim (including spaces).

7h ago 0

Bash

Check Command Exists Before Using It

`command -v` is the portable, fast way to check whether a binary is on $PATH. Avoid `which` (its behavior varies between systems).

7h ago 0

Bash

Disk Space Alert

Cron-friendly script that checks disk usage on each filesystem and emails (or webhooks) if any partition exceeds a threshold.

7h ago 0

Bash

Rotate Logs Manually

If a service doesn't hook into logrotate, you can still rotate a log file yourself in one safe pattern: rename current → .1, truncate the original, signal the process to re-open if needed.

7h ago 0

Bash

docker exec — Drop Into Running Container

`docker exec` is your debugger. Get a shell, inspect env, tail logs, run one-off commands inside a live container.

7h ago 0

Go

errors.Join — Aggregate Multiple Errors

Go 1.20+ ships `errors.Join`, which combines multiple errors into one. Stop accumulating errors in a slice and stringifying yourself — use the standard library.

7h ago 0

Go

sync/atomic — Lock-Free Counter

For simple counters and flags, atomic ops are much faster than `sync.Mutex`. Go 1.19+ added typed wrappers (`atomic.Int64`) — clearer than the raw functions.

7h ago 0

SQL

CREATE TABLE with Constraints

Declare data integrity rules right in the schema — primary keys, foreign keys, unique constraints, NOT NULL, CHECK constraints, defaults. The DB enforces them so application bugs can't corrupt your data.

7h ago 0

PHP

Recursive Directory Walker

Yield every file under a directory using a generator and SPL's RecursiveIteratorIterator. Filter by extension or any other predicate without slurping all paths into memory first.

7h ago 0

Bash

Download with Progress Bar

Show a progress bar for long downloads. wget gives a great built-in bar; curl needs an explicit flag.

7h ago 0

Bash

Tar Archive with Timestamp

Pack up a directory with a date-stamped filename for easy backups. -z for gzip, -j for bzip2, -J for xz (smallest, slowest).

7h ago 0

Go

Variadic Functions

`...T` in the last parameter slot accepts zero or more T values. Pass a slice by suffixing with `...` to spread it. Used everywhere from `fmt.Println` to custom builders.

7h ago 0

Go

Signal Handling with signal.NotifyContext

Go 1.16+ `signal.NotifyContext` returns a context that's canceled on the listed signals. Cleaner than the legacy `signal.Notify(channel)` dance for graceful shutdown.

7h ago 0

PHP

Generate Identicon Avatar

Render a deterministic 5x5 symmetric "identicon" placeholder avatar from any seed (usually a user's email or username). No external service — pure GD.

7h ago 0

Bash

Sum a Column with awk

Awk's default field splitter is whitespace; pass a single character with -F. Perfect for summing the Nth column of a log file or CSV.

7h ago 0

Bash

Get Public IP Address

Several free services return your public IP as plain text. Useful when scripts running behind NAT need to know what address the outside world sees.

7h ago 0