Tags
#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
#utils
#strings
#http
#concurrency
#async
#json
#arrays
#security
#types
#crypto
#database
#dates
#format
Java
Generic Method + Bounded Type Parameters
A method can have its own type parameter independent of the class. `<T extends Comparable<T>>` constrains T to types that can be compared.
@admin
Bash
Array Basics (index + iterate)
Bash 4+ arrays — declare, access by index, get all elements with [@], length with #. The quoting matters: "${arr[@]}" preserves each element; ${arr[@]} word-splits.
TypeScript
Format Relative Time ("3 days ago")
Use the built-in Intl.RelativeTimeFormat to render "3 days ago" / "in 5 hours". Localized for free — pass any BCP 47 locale. No date library needed.
PHP
UPSERT (INSERT ... ON DUPLICATE KEY UPDATE)
A MySQL upsert helper: insert a row, or if a unique key collides, update the same row with the new values. Returns whether the row was inserted (true) or updated (false).
JavaScript
Truncate String
Truncates a string to a maximum character length and appends an ellipsis (or custom suffix). The smart version breaks at the last word boundary to avoid cutting in the middle of a word, making truncated text look natural in card previews, notifications, and list views.
JavaScript
Curry Function
Transforms a multi-argument function into a chain of single-argument functions. Each call returns a new function until all arguments are supplied, then the original function executes. Enables partial application and cleaner function composition pipelines.
JavaScript
Deep Merge Objects
Recursively merges two or more objects, combining nested properties rather than overwriting them. Unlike Object.assign or spread, this preserves deep keys from all sources. Useful for merging configuration objects, default settings with user overrides, and API response patching.
JavaScript
Pipe & Compose
pipe applies a list of functions left-to-right (first function runs first), while compose applies them right-to-left. Both pass the result of each step as input to the next. Fundamental building blocks for functional programming in JavaScript — build data transformation pipelines without intermediate variables.
SQL
Correlated Subquery
A subquery that references the outer query's row. Slower than a JOIN for big result sets but sometimes the most readable expression.
SQL
Median with PERCENTILE_CONT
SQL has no `MEDIAN()` — use `PERCENTILE_CONT(0.5) WITHIN GROUP`. The same function gets you P95, P99, quartiles, etc. for latency analysis.
Rust
Builder Pattern with Method Chaining
Construct complex objects step-by-step with `self`-returning methods. Type-state can enforce required vs. optional fields at compile time — but the simple version is plenty for most cases.
Rust
Format Strings (println! / write!)
Rust's format macros take an inline format string with `{}` placeholders. Named arguments, alignment, precision, debug formatting — all in the format spec.
Python
requests Session with Retry + Timeouts
A pre-configured requests.Session that auto-retries 5xx + connect errors with exponential backoff, applies a default timeout, and uses connection pooling. Use this everywhere instead of bare requests.get().
PHP
Verify a JWT (HS256)
Pair to jwtSign: verify the signature, check the exp claim, and return the decoded payload — or null on any failure. Uses hash_equals for constant-time signature comparison.
PHP
Auto-Reconnect on "MySQL has gone away"
Long-running daemons sometimes lose their MySQL connection mid-run. Wrap your DB calls to retry once after a transient connection-lost error.
SQL
Soft Delete with Partial Index
Set a `deleted_at` timestamp instead of physically removing rows — preserves history and lets you "undelete". Pair with a partial index for fast queries that skip the soft-deleted rows.
SQL
INNER JOIN — Match Rows in Both Tables
Returns rows where the join condition matches in BOTH tables. The default JOIN. Use table aliases (`u`, `o`) for readability when joining 3+ tables.