CommonJS and Serverless

Use lombok-typescript from CommonJS TypeScript projects (Serverless Framework, classic Node require, Jest with module: commonjs) without converting the whole service to ESM.

Requirements

Setting	Value
Node.js	>=22 (see engines in package.json)
module	commonjs or NodeNext with "type": "commonjs" in package.json
moduleResolution	nodenext, node16, or bundler (with esbuild)
Decorators	experimentalDecorators: true for /legacy
Import path	lombok-typescript/legacy (not the main entry)

moduleResolution: node (classic) is not supported — TypeScript cannot resolve the package exports map and you will see TS2307.

Minimal tsconfig

{
  "compilerOptions": {
    "target": "ES2022",
    "module": "NodeNext",
    "moduleResolution": "NodeNext",
    "experimentalDecorators": true,
    "emitDecoratorMetadata": true,
    "strict": true,
  },
  "include": ["src/**/*.ts", ".lombok/**/*.ts", ".lombok/**/*.d.ts"],
}

Import decorators

import 'reflect-metadata';
import { Data, Builder } from 'lombok-typescript/legacy';

@Data
@Builder
export class IncidentPayload {
  incidentId!: string;
  priority!: number;
}

The main package entry exports configuration helpers only. @Data, @Builder, and other decorators are on /legacy or /stage3 by design (ADR-12).

Codegen in CommonJS projects

npx lombok-ts init
npx lombok-ts generate

Include generated companions in tsconfig.json include (see Getting started).

Apply mixins at startup:

import { IncidentPayload } from './incident.dto.js';
import { applyAllGenerated } from '../.lombok/src/incident.dto.lombok.js';

applyAllGenerated({ IncidentPayload });

Use .js extensions in imports when moduleResolution is nodenext, even if source files are .ts.

Serverless Framework + esbuild

When using serverless-esbuild (or similar):

• Set moduleResolution: bundler in tsconfig if the bundler resolves types; otherwise keep nodenext.
• Ensure decorators are not stripped — they must survive to runtime for metadata and codegen markers.
• You do not need "type": "module" in package.json or ESM Lambda handlers for this workflow.

Example in the repo

examples/commonjs-serverless/ mirrors a Serverless + CommonJS consumer. CI runs tsc --noEmit there on every PR.

Troubleshooting

Error	Fix
TS1479 … CommonJS module … ECMAScript module	Upgrade to lombok-typescript@1.0.0+ with dual require types; use moduleResolution: nodenext
TS2305 … no exported member Data	Import from lombok-typescript/legacy, not lombok-typescript
TS2307 … cannot find module lombok-typescript/legacy	Switch from moduleResolution: node to nodenext / node16 / bundler
Decorators have no effect at runtime	Add import 'reflect-metadata' before decorator imports

See also

• Getting started
• CLI
• NestJS integration — Nest apps are usually CommonJS-compatible with the same /legacy import path