Practical guides, worked examples and learning exercises. Browse 128 articles.
Web Security
Map trust boundaries in a file upload workflow. Examine file validation, storage, download authorization and processing limits with a practical checklist.
Web Security
Inspect CSP, HSTS and content-type protections on a response. Learn what each header does and why a present header is not proof of a secure site.
Networking
Use Wireshark display filters to follow DNS questions and answers. Distinguish NXDOMAIN, missing responses and caching in a controlled exercise.
Digital Forensics
Convert offset-aware timestamps to UTC with Python and preserve their originals. Understand clock uncertainty before ordering forensic events.
Digital Forensics
Document training evidence with identifiers, hashes, acquisition notes and custody events. Learn what a manifest records and what it cannot prove.
Node.js
Add explicit request validation to an Express endpoint. Reject wrong types and unknown fields, bound request size and test malformed JSON separately.
Web Development
Create a responsive card grid with CSS Grid, minmax and auto-fit. Prevent narrow-screen overflow and test long content without fixed card heights.
Web Development
Connect form labels, help text and validation messages with semantic HTML. Build an email-field example that works beyond placeholder-only design.
React
Keep a React filtered list consistent by deriving it from props and search input. Learn when an effect is unnecessary and when memoization may help.
JavaScript
Cancel superseded fetch requests and prevent old responses from replacing newer search results using AbortController and a request sequence guard.
JavaScript
Build a small fetch wrapper that checks HTTP status, parses JSON and validates response shape instead of treating every resolved request as success.
Power BI
Choose between a DAX measure and calculated column by understanding row context, filter context and when the result must respond to a visual.
Power BI
Design a small Power BI sales model with a clear fact-table grain, unique dimension keys and checks that prevent duplicated totals.
Data Analysis
Distinguish missing data from zero in pandas. Use nullable types, explicit completeness checks and business rules before filling or dropping values.
Data Analysis
Use pandas merge validate and indicator to catch duplicate lookup keys, unexpected row multiplication and unmatched records in a small sales example.
Python
Turn synthetic log records into a status summary using Counter. Learn parsing rules, rejected-record counts and why aggregates need context.
Python
Handle bad input without hiding programming bugs. Build a Python import loop with specific exceptions, rejected-row reports and clear failure boundaries.
Python
Separate JSON syntax checks from configuration rules in Python. Validate required keys, allowed values and numeric types with clear errors.
Python
Calculate SHA-256 without loading a whole file into memory. Learn chunked reading, digest comparison and the limits of file-integrity checks.
Python
Validate CSV rows with Python, report missing values and invalid numbers, and keep original data intact using a small reproducible example.