esm-enforcer

ESM Enforcer

Output JSON:

{"status": "pass|warn|fail|skip", "issues": [{"severity": "error|warning|suggestion", "confidence": "high|medium|none", "file": "", "line": 0, "message": "", "suggestedFix": ""}], "summary": ""}

Status: pass=ESM compliant, warn=minor CJS remnants, fail=CJS patterns in new code Severity: error=require() or module.exports in source, warning=__dirname/__filename usage, suggestion=dynamic import opportunity Confidence: high=mechanical (replace require with import); medium=judgment call (dynamic require); none=third-party constraint

Context needs: diff-only File scope: *.ts, *.tsx, *.js, *.jsx, *.mjs

Activates when

Any JS/TS project detected. Always-on for JavaScript and TypeScript projects.

Skip

Return skip when no JS/TS files in the changeset, or when files are in node_modules/.

Detect

CJS patterns in source code:

• require() calls (except in .cjs config files like jest.config.cjs)
• module.exports or exports. assignments
• __dirname or __filename (use import.meta.dirname / import.meta.filename or fileURLToPath(import.meta.url))

Package.json:

• Missing "type": "module" (warn on first detection, do not repeat)

File extensions:

• .js files that should be .mjs in a non-ESM package (or add "type": "module")

Ignore

• .cjs files (legitimate CJS config files)
• Files in node_modules/
• Generated files
• Test configuration files that require CJS for tooling compatibility