js-fp-review

JS FP Review

Scope:

• **/*.js
• **/*.ts
• **/*.jsx
• **/*.tsx
• **/*.mjs
• **/*.cjs Cites: [adversarial-review-protocol]

Scope: JavaScript and TypeScript files only (.js, .ts, .jsx, .tsx, .mjs, .cjs). Skip this agent entirely if the project has no JS/TS files.

Output JSON: per ${CLAUDE_PLUGIN_ROOT}/knowledge/review-agent-output-contract.md (Whole-file load: short, canonical schema).

Status: pass=no mutations or impure patterns, warn=only style/point-free suggestions, fail=external mutation or a buried side effect Severity: error=external state mutation or a side effect buried inside a value-returning computation, warning=local mutation, suggestion=style (point-free/composition) Confidence: high=mechanical substitution (push→spread, let→const); medium=pattern clear but spread vs clone depends on usage, or extracting a console/DOM side effect; none=requires human judgment (intentional mutation for performance, or removing a non-deterministic read whose value is actually used downstream)

Context needs: diff-only

Skip

Return {"status": "skip", "issues": [], "summary": "No JS/TS files in target"} when:

• No .js, .ts, .jsx, .tsx, .mjs, or .cjs files exist in the target
• All target files are non-JavaScript/TypeScript

Detect

Variable declarations:

• let never reassigned → use const
• var → use const/let
• Exception: prefixes mut/mutable/_ indicate intentional mutability

Array mutations (flag and suggest):

• .push() → [...arr, item]
• .pop() → arr.slice(0, -1)
• .shift() → arr.slice(1)
• .unshift() → [item, ...arr]
• .splice() → slice + spread
• .reverse() → [...arr].reverse() or toReversed()
• .sort() → [...arr].sort() or toSorted()
• .fill() → map
• Exception: mutations on spread copies [...arr].sort() allowed

Object mutations:

• param.prop = value (parameter mutation)
• param[key] = value (parameter mutation)
• delete param.prop
• Object.assign(existingObj, ...) → spread or new object target
• Exception: this.property in class methods allowed