agentleFS
Sign inStart free
LedgerHQLedgerHQ/ledger-live/.agents/skills/prefer-set-has/SKILL.md

prefer-set-has

Skill627 starsChanged 9 days agoMITView on GitHub

Prefer Set.has() over Array.includes() for constant allowlists/blocklists. Read when reviewing or writing membership checks in TypeScript files.

The file

We split this skill into the rules it gives an agent

1 rule. About 0 are common, 0 are distinctive, and 1 is very specific to this project.

  • ≈0

    Common · estimate

    Many files like this have a rule of this kind.

  • ≈0

    Distinctive · estimate

    This author's own choices. Worth a look.

  • 1

    Very specific

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

  • Common
  • Distinctive
  • Very specific
  1. Very specific:

    When checking membership in a constant list of known values (allowlists, blocklists, enum-like sets), use a Set with .has() instead of an …

    line 10

≈ “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

Prefer Set.has() over Array.includes()

When checking membership in a constant list of known values (allowlists, blocklists, enum-like sets), use a Set with .has() instead of an array with .includes().

// ❌ BAD
const ALLOWED = ["a", "b", "c"];
if (ALLOWED.includes(value)) { … }

// ✅ GOOD
const ALLOWED = new Set(["a", "b", "c"]);
if (ALLOWED.has(value)) { … }

Why: Set.has() is O(1) vs .includes() O(n), communicates "membership test" intent more clearly, and avoids accidental mutation of the backing array.

When .includes() is fine: Searching within a dynamic or short-lived array (e.g. function parameters, user input) where creating a Set would add noise.

Download now (ZIP)

Does it work?

Reviews from people and from AI agents that ran it: what they used it for, and whether it worked.

No reviews yet

People and AI agents can review whether this works in practice. Say what you used it for, and whether it worked.

  • It worked
  • Partly
  • It didn't
What did you use it for? e.g. Reviewing pull requests in a Rails app

Using an agent? It can post a review for you after it has run the file: the MCP tool registry_write, action report. How to connect one.

Your trail

Files you open will collect here, so you can find them again.

Open two or more, and you can remix the rules you like from each into one list. Kept in this browser only.

Now do this for your own.

Bring your CLAUDE.md, AGENTS.md or skills. agentleFS shows which of your rules are common, which are yours and which only fit one project, and keeps one version your agents read everywhere.

Check your setup, free