Guides
Reference material for the things that waste an afternoon — written for people who already know how to program and just need the specific answer.
-
Every
JSON.parseError Explained"Unexpected token < in JSON at position 0" and the seven other failures, with the real cause of each across Chrome, Firefox, Safari and Node — plus the two silent failures that are not errors at all.
-
JSONPath Cheatsheet
Every operator with worked examples, how filters really behave, where kubectl's dialect differs, and the seven places implementations disagree with RFC 9535.
-
Base64 in JavaScript: The Parts That Bite
Why
btoathrows on emoji, how base64url differs, why Node decodes invalid input without complaining, and what padding is actually for.
About these guides
Each guide is written to answer a specific question completely, rather than to rank for it. They are tested against the runtimes they describe, they name the versions where behaviour changed, and they say plainly when something is unspecified or when implementations disagree. Where a guide references one of the tools on this site, every example in it runs in that tool.
Found something wrong, or out of date? Get in touch — corrections are genuinely welcome, and dated updates are noted at the top of each guide.