reflect-metadata

typescript-reflect-metadata.ts

import 'reflect-metadata';

type MyDecObj = {a: number};

const myDecKey = Symbol('design:myDec')

function MyDec(obj: MyDecObj) {
    return Reflect.metadata(myDecKey, obj);
}

@MyDec({a: 100})
class A {

    @MyDec({a: 0})
    public property: string;
}

const inst = new A;

const obj = Reflect.getMetadata(myDecKey, inst, 'property');

console.log(obj);