Intermediate terms
Unhandled Promise Rejection
ES2015
An unhandled Promise rejection occurs when a rejected Promise has no .catch() or try/catch handler — Node.js 15+ terminates the process on unhandled rejection by default.
6mo ago
JavaScript intermediate
Unicode & Multibyte Regex
PHP 5.3+
2
The u flag enables UTF-8 mode and \p{} Unicode property classes — essential for correctly matching text in any language.
6mo ago
Regex intermediate
Uptime Monitoring
PHP 5.0+
Continuously checking that your application is reachable and responding correctly — synthetic monitoring (scripted checks from external locations) vs real user monitoring (RUM from actual traffic).
6mo ago
Observability intermediate
Ubiquitous Language (DDD)
2
A shared vocabulary between developers and domain experts, used consistently in code, tests, documentation, and conversation.
6mo ago
Architecture intermediate
Unicode Fundamentals
PHP 5.0+
7
Unicode assigns every character a code point — UTF-8 encodes these as 1-4 bytes, making it the universal encoding for text on the web.
6mo ago
i18n intermediate
Union Types (PHP 8.0)
PHP 8.0+
2
Allow a parameter, return value, or property to accept multiple specified types, declared as TypeA|TypeB.
6mo ago
PHP intermediate
UPSERT
PHP 5.0+
An atomic INSERT-or-UPDATE operation — inserts the row if it does not exist, updates it if it does — eliminating the race condition of a separate check-then-insert.
6mo ago
Database intermediate
Using AI APIs in PHP
PHP 8.0+
1
Integrating LLM APIs (OpenAI, Anthropic, Gemini) into PHP applications — for text generation, classification, extraction, and embedding-based search.
6mo ago
AI / ML intermediate
UUID vs ULID vs Auto-Increment
PHP 7.0+
Primary key strategies: auto-increment is simple and fast, UUID v4 is globally unique but random (poor index performance), UUID v7 and ULID are sortable globally unique IDs.
6mo ago
Database intermediate