I am developing a multi-language Angular4 application with VS Code. 

The router has to be like this: 

> 
> localhost/en-us/visions
> 
> 
> 

I have a class called TranslateHelper: 

```
import { ActivatedRoute } from '@angular/router';
export class TranslateHelper {
   private currentLanguage: string;
   private defaultLanguage = 'de-de';

   constructor( private route: ActivatedRoute) {}

   public getCurrentLanguage() {
      this.route.params.subscribe(params => {
        this.currentLanguage = params.lang;
   });

   return this.currentLanguage;
  }
}

```

the app-routing.module is: 

```
const routes: Routes = [
  { path: ':lang/visions', component: VisionsComponent},
];

```

and in the footer I am trying to add the language in the URL: 

```
export class FooterComponent implements OnInit {
  public lang;

  constructor(private translateHelper: TranslateHelper) { }

  ngOnInit() {
    this.lang = this.translateHelper.getCurrentLanguage();
  }

}

```

HTML:

```
    <li><a [routerLink]="[lang, 'visions']">Visions</a></li>

```

I do not receive any failure, but the lang in the footer is always undefined, exactly as the params.lang is.

can anybody tell me how can I fix it? thank you anyway.