Bash

Get Script's Own Directory

The "where am I" boilerplate that every nontrivial bash script needs. Resolves symlinks correctly with realpath, falls back gracefully if realpath is missing.

5h ago 0

Bash

Hash File (SHA-256)

Compute and verify file checksums for downloads, backups, and integrity audits. sha256sum on Linux; shasum -a 256 on macOS.

5h ago 0

Go

context.Context — Cancellation & Deadlines

`context.Context` propagates deadlines, cancellation, and request-scoped values down a call chain. EVERY blocking / long-running function should take a `ctx context.Context` as its first parameter.

5h ago 0

PHP

Secure Session Bootstrap

Start a session with all the security flags you should always set: HttpOnly, SameSite=Strict, Secure on HTTPS, custom name, and an idle-timeout regeneration.

5h ago 0

PHP

Set Cookie with Modern Options

PHP 7.3+ accepts an options array on setcookie() — use it. Sets HttpOnly, Secure on HTTPS, SameSite=Lax by default, and a sensible expiry.

5h ago 0

Python

asyncio Concurrency Limiter (Semaphore)

Run hundreds of coroutines but cap how many are in-flight at any moment. asyncio.Semaphore inside the task body is the cleanest way to "do at most 10 of these at a time."

5h ago 0

Python

Password Hashing with hashlib.scrypt

Hash a password with the stdlib scrypt (memory-hard, slow by design — resistant to GPU/ASIC attacks). Stores salt + parameters inline so verification doesn't need a separate config.

5h ago 0

Go

sync.Pool — Reuse Allocations

`sync.Pool` keeps a pool of reusable objects to reduce allocator pressure in hot paths. Good for byte buffers, JSON encoders, or anything you allocate frequently and only need briefly.

5h 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.

5h ago 0

Bash

Encrypt / Decrypt File with openssl

Symmetric AES-256-GCM encryption of arbitrary files. Use PBKDF2 + a password (good for backups) or pass an explicit key.

5h ago 0

Java

CompletableFuture — Async Chains

`CompletableFuture` is the idiomatic way to compose async work. `thenApply` for sync transforms, `thenCompose` for async chains (flatMap), `exceptionally` for fallback on failure.

5h ago 0

JavaScript

Detect Dark Mode Preference

Reads the user's OS-level dark mode preference using the prefers-color-scheme media query and watches for live changes. Useful for initialising theme state before any user interaction and reacting automatically when the user switches their system theme without reloading the page.

5h ago 0

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.

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Go

http.Client with Timeout

`http.DefaultClient` has no timeout — a hung server can hang your whole program forever. ALWAYS use a custom client with an explicit timeout for outbound requests.

5h ago 0

HTML

Datalist — Autocomplete Suggestions

`<datalist>` attaches type-ahead suggestions to any text input. The user can still type something custom — it's suggestions, not a hard constraint.

5h ago 0

SQL

Pattern Matching — LIKE / ILIKE / SIMILAR

`LIKE` uses `%` (any string) and `_` (single char). PostgreSQL `ILIKE` is case-insensitive. For real regex, reach for `SIMILAR TO` (POSIX) or `~` (PostgreSQL).

5h ago 0

SQL

Window Function vs N+1 Query

Don't fetch a list, then loop in code to count each parent's children. Use a window function or a single GROUP BY — turn 1,001 queries into 1.

5h ago 0

HTML

Login Form (with autocomplete hints)

A complete login form with the autocomplete attributes that browsers + password managers depend on. Missing these causes 1Password, Bitwarden, and Chrome to mis-detect the form.

5h ago 0

HTML

Registration Form (new-password + email-verify)

`autocomplete="new-password"` tells password managers to OFFER a generated password instead of filling an existing one. `autocomplete="email"` and `inputmode="email"` give phones the right keyboard.

5h ago 0

Bash

Slice Bash Array

Bash supports Python-like array slicing via ${arr[@]:offset:length}. Lets you take/skip elements without external tools.

5h ago 0

Bash

Check If Array Contains Element

A pure-bash membership test using `=~` or by iterating. Both are useful — pick by readability vs. speed.

5h ago 0

Go

Functional Options Pattern

Replace giant config structs with a variadic list of `Option` functions. Lets you add optional parameters later without breaking existing callers. The standard Go API design for constructors.

5h ago 0

SQL

FULL OUTER JOIN / CROSS JOIN

`FULL OUTER` keeps unmatched rows from BOTH sides. `CROSS JOIN` is the Cartesian product — every row of A paired with every row of B. Rare but useful for date-spine and matrix generation.

5h ago 0

SQL

TRUNCATE vs DELETE

`DELETE` is logged per-row and respects triggers; `TRUNCATE` deallocates whole pages and resets the table to empty. `TRUNCATE` is much faster on large tables but has caveats (no WHERE, can't be rolled back in some DBs).

5h ago 0

HTML

Select with Optgroup

`<optgroup label="...">` visually groups options inside a `<select>`. Renders as a non-selectable header in every browser; screen readers announce the group as context.

5h ago 0

SQL

Array Columns (PostgreSQL)

Native array columns avoid an extra join for "small list of things per row" patterns — tags, categories, allowed_roles. Combine with GIN index for fast `@>` / `&&` operators.

5h ago 0

PHP

Set Nested Value by Dot Path

Mutate a nested array by dot path, auto-creating any intermediate arrays. Companion to getPath; together they replace a lot of isset+array_key_exists ladders.

5h ago 0

SQL

DELETE with JOIN / USING

Delete rows from one table conditional on a related table. PostgreSQL uses `USING`; MySQL uses join syntax in the DELETE. Run as a SELECT first to verify what you're about to remove.

5h ago 0

SQL

MERGE — One Statement for INSERT + UPDATE + DELETE

`MERGE` (standard SQL, PostgreSQL 15+, SQL Server, Oracle) is a single statement that combines INSERT/UPDATE/DELETE driven by joining a source against a target. Heavy artillery for reconciliation jobs.

5h ago 0

SQL

EXPLAIN / EXPLAIN ANALYZE

`EXPLAIN` shows the query plan; `EXPLAIN ANALYZE` actually runs it and shows real timings. The first tool when a query is slow — look for sequential scans on big tables.

5h ago 0