FAQ

Which entrypoint should I import?

Use @litert/decorator for modern TypeScript standard decorators. Use @litert/decorator/legacy for old experimental decorators. Use @litert/decorator/compatible when one decorator implementation must support both emitted argument shapes.

Are @litert/decorator and @litert/decorator/modern different?

No. Both import paths resolve to the same modern implementation. The default path is shorter, while @litert/decorator/modern is useful when code wants to be explicit beside /legacy or /compatible imports.

Why does modern decorator code need types: ["@litert/decorator"]?

The modern entrypoint installs a Symbol.metadata polyfill and provides typings for decorator metadata support. Add the package to compilerOptions.types so TypeScript sees those global declarations.

Can compatible decorators support parameter decorators?

No. Legacy TypeScript decorators support parameter decorators, but modern standard decorators do not provide matching parameter decorator support. The compatible entrypoint therefore documents class and member decorators only.

What is the difference between validateArgs, withArgsCheck, create, and compose?

API	Purpose
validateArgs	Check whether raw decorator callback arguments match one decorator kind.
withArgsCheck	Wrap a callback and throw TypeError when it is applied to the wrong decorator kind.
create	Build a checked decorator from a normalized callback or compatible options object.
compose	Build one decorator that applies several decorators in order.

How are accessor-like general decorators dispatched?

General decorators use the priority accessor > getter == setter. The same rule applies to static accessor, static getter, and static setter decorators.

Should I use legacy decorators for new code?

Prefer modern decorators for new TypeScript code unless the project already depends on experimentalDecorators behavior or parameter decorators. The legacy API remains available for existing Stage 2 decorator code.

How do I store metadata with legacy decorators?

Use the reflect-metadata module. Do not use getMetadataContainer — that API is designed for modern (Stage 3) decorators only. Install reflect-metadata and import it once at your entry point, then use Reflect.defineMetadata() and Reflect.getMetadata() to write and read metadata.

import 'reflect-metadata';
import { Classes } from '@litert/decorator/legacy';

function entity(): Classes.ICallbackFn {

    return Classes.create((ctx) => {
        Reflect.defineMetadata('entity', true, ctx.constructor);
    });
}

@entity()
class User {}

console.log(Reflect.getMetadata('entity', User)); // true