Typescript metadata / decorators

Boot.ts

import Main from "./main";
import {Program} from "./program";

Main.bootstrap(Program);

class-metadata-decorator.ts

import "reflect-metadata";

export function classMetadata(metadata: IMetadata){
    return function (target: Function) {
      Reflect.defineMetadata("metadata", metadata, target);
  }
}

log-decorator.ts

export function log(target: Object, propertyKey: string, descriptor: TypedPropertyDescriptor<any>) {
    
    let originalMethod = descriptor.value;
  
    descriptor.value = function(...args: any[]) {
        console.log("The method args are: " + JSON.stringify(args));
        let result = originalMethod.apply(this, args);               
        console.log("The return value is: " + result);              
        return result;                                              
    };
    
    return descriptor;
}

Main.ts

import "reflect-metadata";


export default class Main {
   
    static bootstrap(program:any) {
        
        var programMetadata = Main.GetMetadata(program);        
        //Print found metadata in class
        console.log(programMetadata);

        //Log with be printed when calling getData
        new program().getData(5);

        //output
        //[ { name: 'field1', value: 'value1' },
        //  { name: 'field2', value: 'value2' } ]
        //  The method args are: [5]
        //The return value is: Data1,Data2,Data3
    }
     
    private static GetMetadata(obj:any): Array<IMetadata> {
          var componentInstance = new obj();
          return Reflect.getMetadata("metadata", componentInstance.constructor).Metadata;
    }
    
}

Program.ts

import {classMetadata} from "./decorators/class-metadata-decorator";
import {HttpService} from "./services/http-service";
import {log} from "./decorators/log-decorator";

@classMetadata({
   Metadata: [
       {name:"field1", value:"value1"},
       {name:"field2", value:"value2"}
   ]
})
export class Program  {
    
    constructor(private httpService:HttpService) {
        this.httpService = new HttpService();
    }
    @log
    getData(value:number){
        return this.httpService.getData(value);
    }
}