Intermediate terms
Cross-Version Compatibility Testing
PHP 7.0+
Testing PHP code across multiple versions uses CI matrix builds, phpenv/phpbrew, Docker multi-version setups, and static analysis to catch compatibility issues before deployment.
3mo ago
php intermediate
CSS :has() Selector
CSS :has() is a parent selector — .card:has(.badge) matches a .card that contains a .badge — enabling styles that depend on children or siblings, which previously required JavaScript.
3mo ago
frontend intermediate
callable vs Closure vs First-Class Callable
PHP 7.1+
PHP has three callable forms: loose callable (string/array), typed Closure, and PHP 8.1 first-class callables (strlen(...)) — prefer Closure or first-class callables for type safety.
3mo ago
php intermediate
Circular References & Memory Implications
PHP 5.3+
Circular references between objects prevent PHP's reference counting GC from freeing memory — PHP's cycle collector handles them but with overhead.
3mo ago
php intermediate
Classic Closure-in-Loop Bug (var vs let)
ES2015
The most common JavaScript closure bug: using var in a for loop captures the loop variable by reference so all callbacks see the final value — fixed by using let which creates a new binding per iteration.
3mo ago
javascript intermediate
Constructor Promotion + readonly Together
PHP 8.1+
PHP 8.1+ allows readonly in constructor promotion: public function __construct(public readonly string $name) — the cleanest way to write immutable value objects.
3mo ago
php intermediate
Custom Error Handlers (set_error_handler)
PHP 5.0+
set_error_handler() lets you replace PHP's default error handling with a custom callback — essential for logging, alerting, and graceful degradation.
3mo ago
php intermediate
Client-Side Sanitisation
ES2015
3
DOMPurify and the Sanitizer API remove dangerous HTML before insertion — complementing PHP's server-side htmlspecialchars for rich-text scenarios.
3mo ago
javascript intermediate
CSRF Token Handling in Fetch & Axios
ES2017
Including PHP-generated CSRF tokens in JavaScript requests — reading from meta tags or cookies and attaching to every state-changing request.
3mo ago
javascript intermediate
Cache Warming Strategies
PHP 5.0+
Pre-populating a cache before traffic arrives — preventing the cold-start thundering herd where every request misses a cold cache simultaneously after a deploy.
3mo ago
performance intermediate
Character Encoding
PHP 5.0+
1
How text is stored as bytes — ASCII (128 chars), Latin-1 (256 chars), UTF-8 (1-4 bytes, backwards compatible), and UTF-16 are the key encodings developers encounter.
3mo ago
i18n intermediate
Circular Buffer / Ring Buffer
PHP 5.0+
1
A fixed-size array treated as circular — the write pointer wraps around when it reaches the end, overwriting the oldest data. Used for logs, audio streaming, and producer-consumer queues.
3mo ago
data_structures intermediate
CLI Tools with argparse & Click
Python 3.6+
2
Building Python command-line tools — argparse (stdlib) for simple tools, Click (decorator-based) for complex CLIs with subcommands, type coercion, and better help formatting.
3mo ago
python intermediate
Cloud CDN
CloudFront, Fastly, Cloudflare — caching at edge PoPs worldwide reducing latency and origin load.
3mo ago
cloud intermediate
Cloud Cost Optimisation
Systematically reducing cloud spend without reducing capability — right-sizing instances, using reserved/spot pricing, eliminating waste, and architecting for cost from the start.
3mo ago
cloud intermediate
Cloud Message Queues
Managed queue services — AWS SQS, Google Pub/Sub — durable scalable queuing without managing RabbitMQ infrastructure.
3mo ago
cloud intermediate
Cloud Monitoring Tools
1
CloudWatch (AWS), Cloud Monitoring (GCP), Azure Monitor — auto-collect infrastructure metrics but need explicit instrumentation for application metrics.
3mo ago
cloud intermediate
Cloud VPC & Networking
Virtual Private Cloud — private subnets for databases/workers, public subnets for load balancers only, security groups as stateful firewalls.
3mo ago
cloud intermediate
Cloud-Native Patterns
PHP 5.0+
Stateless services, externalised config, health checks, graceful shutdown, and immutable infrastructure — the 12-Factor App extended for containers.
3mo ago
cloud intermediate
Code Freeze & Release Management
A period stopping new features entering a release branch — feature flags and continuous delivery eliminate the need for long freezes.
3mo ago
general intermediate