typescript-best-practices
Skill0 starsChanged 17 days agoMITView on GitHub
TypeScript best practices. Use when reading or editing any .ts or .tsx file.
77 other projects use a version of this, 55 of them edited.
Adopted by
Most recently taken up by
- Yeachan-Heo/oh-my-claude-sisyphustheir own version, first seen Nov 8, 2026
- caidanw/skillstheir own version, first seen Nov 8, 2026
- trpc/trpcedited, first seen Nov 8, 2026
- Yeachan-Heo/oh-my-claudecodetheir own version, first seen Nov 8, 2026
- endqwerty/endstackedited, first seen Nov 8, 2026
- tristanphvn/keeledited, first seen Nov 8, 2026
Other versions77 projects use a version of this.
Word for word · 0
None found.
Edited · 55
- trpc/trpc★ 41k97% same
- backnotprop/pstack★ 3.8k97% same
- jtaroreh/agystack★ 12892% same
- uzairansaruzi/p3-stack★ 12697% same
- dsebban/skills★ 7192% same
- overextended/skills★ 2223% same
- creedants/pstack-t3★ 1899% same
- painhardcore/pstack★ 1898% same
- Scino/fstack★ 1889% same
- korallis/skills-collection★ 1492% same
45 more not listed
Wrote their own version · 22
- Yeachan-Heo/oh-my-claude-sisyphus★ 41ksame name
- Yeachan-Heo/oh-my-claudecode★ 41ksame name
- baekenough/oh-my-customcode★ 42same name
- TheOnlyFusionCube/potetos-for-everyone★ 21same name
- caidanw/skills★ 11same name
- flpbalada/fb-skills★ 8same name
- robconery/kolea★ 7same name
- ex3ndr/skills★ 5same name
- kelesmert/turnlens★ 4same name
- requie/endostack★ 4same name
12 more not listed
How matches are found. Word for word: the exact same text. Edited: shares passages with this file (“99% same” means 99% of its five-word phrases also appear here; 10% or more counts). Their own version: similar meaning, or, weakest, the same name. We can’t tell which project had it first. Projects are counted among the 200 most-starred candidates, and mentions are links to the repository we found, up to 50 per site, so both counts are a floor.
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The file
We split this skill into the rules it gives an agent
1 rule. 0 are common, 1 is distinctive, and 0 are very specific to this project.
0
Common
Most of the 26 edited versions we read keep these.
1
Distinctive
This author's own choices. Worth a look.
0
Very specific
Tied to their project's names, files or tools. Probably skip.
- Common
- Distinctive
- Very specific
- Distinctive: line 6
Read the Codex runtime adapter once per session before using this skill.
“Common” is measured: kept by at least 6 in 10 of the 26 edited versions of this file we could read. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.
Files
Read the Codex runtime adapter once per session before using this skill. Its tool, model, history, and authorization mappings apply to all linked instructions.
TypeScript best practices
Apply the type-system-discipline principle skill first.
| Rule | Summary |
| Discriminated unions | Model variants with a kind literal discriminant so impossible states can't be represented. No optional-field bags. |
| Branded types | Brand primitives with & { readonly __brand: "X" } so they can't be mixed up. Validate once at the boundary. A brand comes from a verifying type guard (input is AgentId), never from as. |
| Constructive modeling | Build the shape so the illegal value can't be constructed. [T, ...T[]] for non-empty, [T, T][] for even length, start plus duration for a range. Not a runtime guard, not a wish for refinement types. |
| Simplest total type | Keep T[] while every operation on it stays total. Strengthen to NonEmpty<T> only where the loose type forces !, a cast, or a "should never happen" throw. |
unknown over any | External data is unknown. |
| Schemas before guards | Before hand-writing a property-by-property type guard, use the repository's runtime schema library and infer the type from the schema, such as z.infer. |
No as casts | Every as is a runtime crash waiting. Cast only after validation. |
| Narrowing hierarchy | Discriminant switch > in operator > typeof/instanceof > user-defined type guard > as. |
| Type guards | Must verify the claim. A lying guard is worse than as because the bug hides behind a name that says it's safe. Name them isX or hasX. |
| Exhaustiveness | Inline const _exhaustive: never = x; in default arms so the compiler errors when a new variant is added. |
satisfies over as | Validates the value without widening literal types. |
| Boundary validation | Parse where data crosses in, into a named domain type. Record<string, unknown> (however spelled) stops at that parse. Trust types inside. See the boundary-discipline principle skill. |
| Schema-derived types | Reach for Pick/Omit/Parameters/ReturnType/Awaited/typeof before declaring a new interface. |
| Object args | Pass objects, not positional, so argument order is self-documenting. Skip on hot paths (per-frame render, tokenizers, parsers). |
| Real tests | Don't mock what you can run. Prefer the framework's real test primitives with leak/disposable checks, and verify UI in a running build. Mock only what you can't run locally. |
| Structured telemetry | Prefer structured logger diagnostics with enough context to debug from an id. No console.log in shipped code. |
Examples: references/patterns.md.
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