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ccheneyccheney/robust-skills/skills/modern-javascript/SKILL.md

modern-javascript

Skill60 starsChanged 2 months agoMITView on GitHub

Implement or debug JavaScript language behavior, including promise completion, async iteration, mutation, and runtime compatibility. Use for ECMAScript semantics or polyfill/transform choices; not unrelated framework or TypeScript type design.

1 other project uses a version of this.

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  • Other versions1 project uses a version of this.

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    Wrote their own version · 1

    1. cmnemoi/skills★ 0same name

    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.

  • In this repository10 other files it gives its agents.

The file

We split this skill into the rules it gives an agent

8 rules. About 0 are common, 5 are distinctive, and 3 are very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈5

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 3

    Very specific

    Tied to their project's names, files or tools. Probably skip.

  • Common
  • Distinctive
  • Very specific
  1. Distinctive:

    Keep specification status, runtime support, and toolchain support separate.

    line 8
  2. Very specific:

    Use the relevant JavaScript, required behavior, and declared runtime as input.

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  3. Distinctive:

    Prefer a supported standardized feature.

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  4. Distinctive:

    Keep mutation, property access, iterator consumption, evaluation order, error propagation, and concurrency behavior intact when modernizing.

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  5. Very specific:

    Treat iterator helpers as lazy and single-pass.

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  6. Very specific:

    Do not use forEach(async ...) when completion must be awaited.

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  7. Distinctive:

    Do not introduce withdrawn Records & Tuples syntax or silently switch between legacy and standard-style decorator semantics.

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  8. Distinctive:

    Use frozen ECMA-262 editions for edition membership, TC39 proposals for proposal status, and official runtime/toolchain documentation for …

    line 45

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.
Files
SKILL.md

Modern JavaScript

Keep specification status, runtime support, and toolchain support separate. The user's explicit instructions take precedence over this skill's guidelines.

Work against the target

Use the relevant JavaScript, required behavior, and declared runtime as input. Inspect engines, browser targets, lockfiles, and build configuration as needed for the feature. Do not invent a baseline or upgrade runtimes merely to use newer syntax.

Prefer a supported standardized feature. A proposal can fit when the user/project chooses it and a maintained transform or polyfill implements the required revision. Bundled edition and support tables are dated snapshots; verify changing status against the sources below.

Preserve semantics

  • Keep mutation, property access, iterator consumption, evaluation order, error propagation, and concurrency behavior intact when modernizing.
  • Distinguish syntax transforms from runtime polyfills. TypeScript declarations do not supply missing runtime APIs.
  • Treat iterator helpers as lazy and single-pass; Array.fromAsync consumes sequentially, while Promise.all observes already-started work concurrently.
  • Do not use forEach(async ...) when completion must be awaited. Rejection and timeouts do not cancel underlying work by themselves.
  • Distinguish host APIs such as fetch and structuredClone from ECMA-262 features, and Intl from the separate ECMA-402 standard.
  • Do not introduce withdrawn Records & Tuples syntax or silently switch between legacy and standard-style decorator semantics.

Deliver the requested code or explanation, noting a required compatibility path when relevant. Verify changed behavior and any fallback that ships; select checks proportional to the change rather than requiring every project check for a syntax answer.

References

Load the semantic or compatibility topic needed, not every edition.

TaskReference
Runtime targets, Babel, TypeScript, polyfillsCOMPATIBILITY.md
Async functions and early annual additionsES2016-ES2017.md
Object spread, async iteration, RegExp, flatteningES2018-ES2019.md
Classes, property checks, change-by-copyES2022-ES2023.md
Grouping, promise resolvers, buffers, Unicode setsES2024.md
Set/iterator helpers, import attributes, RegExpES2025.md
ES2026 additions such as Array.fromAsyncES2026.md
Temporal, resource management, proposals, withdrawn syntaxUPCOMING.md
Promise combinators and error behaviorPROMISES.md
Pools, retries, cancellation, async iterationCONCURRENCY.md
Compact syntax lookupCHEATSHEET.md

Use frozen ECMA-262 editions for edition membership, TC39 proposals for proposal status, and official runtime/toolchain documentation for availability.

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