Practical developer guides
Practical guides to JSON, Markdown, JWT, encoding, cron, regex and HTTP debugging. Search by topic and try reproducible examples with browser-local tools.
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10 of 10 guidesJSON large integer precision: find and prevent lost digits
Reproduce lost digits with 9007199254740993, compare raw JSON with parsed values, and learn when to use string IDs or BigInt.
Read guide TIMESTAMPUnix seconds vs milliseconds: fix dates and time zones
Compare seconds, milliseconds and ISO dates for one instant. Diagnose unit errors, UTC versus local display, and verify a date round trip.
Read guide MARKDOWNMarkdown README formatting: tables, task lists and line breaks
Build a release checklist with tables, task lists and code blocks. Fix line breaks and choose between Markdown source and HTML export.
Read guide JWTCan you trust a decoded JWT? Signatures and expiry claims
Inspect a three-part JWT, read its header and payload, convert exp seconds to UTC, and separate decoding from signature and permission checks.
Read guide BASE64Base64 vs Base64URL: UTF-8, padding and round-trip checks
Encode Hello, 世界, compare alphabets and padding, and understand UTF-8 text limits when decoding JWT segments or binary data.
Read guide URLHow to encode URL parameters: plus signs, Unicode and double encoding
Compare component and full-URL encoding with a+b &中. Understand %20, + and %2520, then verify a query-value round trip.
Read guide YAMLYAML to JSON type changes: quotes, comments and large integers
Round-trip configuration values to inspect strings, booleans, arrays and indentation. Understand lost comments and rejected large integers beyond formatting.
Read guide CRONFive-field cron and time zones: why a job runs at the wrong time
Break down a weekday 09:00 cron schedule. Compare UTC and Shanghai, then inspect day-field combinations, daylight saving and platform rules.
Read guide REGEXRegex escaping and flags: why the same pattern stops matching
Compare backslashes in raw patterns, JavaScript strings and JSON using order IDs. Practice g, i, m and s flags and inspect capture groups.
Read guide HTTP-STATUSHTTP 401, 403, 404, 502 and 504: diagnose the response
Distinguish authentication, permissions, missing resources and gateway errors. Correlate headers, bodies and request IDs instead of guessing from a code alone.
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