Development & Web
What these guides have in common: the rule itself is one sentence, but "which rule applies in which position" decides whether you are right. URL encoding fits in a sentence, yet confusing "encode the whole URL" with "encode one parameter value" produces signatures that never match.
Every guide gives the decision criterion first and the conclusion second, including what the failure looks like when you pick wrong. Debugging guides are ordered from the most-overlooked cause to the least likely one, not from the most common guess.
- Number Bases: Hex, Two's Complement, and Float ErrorsWhy hex always comes in pairs, how computers store negative numbers, why 0.1 + 0.2 is not 0.3, and where JavaScript silently loses integer precision.
- HTML Escaping and XSS: The Five CharactersEscaping angle brackets is not enough. The five characters that must be escaped, why the right rule depends on where the value lands, and why you escape on output rather than on input.
- Regex Patterns Developers Actually UseEmail, URL, IP, date, phone numbers — the patterns you need weekly, why most of them are wrong, and the two features (lookbehind, lazy quantifiers) that trip people up when porting between languages.
- Unix Timestamps: Seconds, Milliseconds, and Time ZonesWhy a 13-digit timestamp breaks your date conversion, why Unix time has no time zone but your display does, and the two places where 32-bit time still runs out.
- URL Encoding: %20, Plus Signs, and Double EncodingWhy a space is sometimes %20 and sometimes +, what encodeURI and encodeURIComponent actually differ on, why Chinese text becomes three percent signs, and why your signature never matches.
- YAML, JSON or TOML: Picking a Config FormatYAML is pleasant until indentation or the Norway problem bites. JSON has no comments. TOML is boring on purpose. What each format is actually good at, with the failure modes that decide the choice.