false-cjs-esm

Detect format mismatch between declaration files and JS files (FalseCJS/FalseESM)

Property	Value
Rule ID	types/false-cjs-esm
Category	types
Severity	🔴 error
Fixable	No

What it Checks

Detects when a .d.ts file uses ESM syntax (export {}) but the corresponding .js file is CommonJS, or vice versa. This mismatch (known as FalseCJS or FalseESM) causes runtime errors for consumers.

Configuration

Disable this rule:

tspub check --ignore-rules "types/false-cjs-esm"

Or in tspub.config.ts:

export default {
  check: {
    severityOverrides: {
      "types/false-cjs-esm": "off",  // or "warning", "error", "info"
    },
  },
};