How to translate ts variables in angular 4?

Question

How to translate angular variables in template or ts file itself
HTML code - someComponent.html

<button (click)="changeLang('en')">En</button>  
<button (click)="changeLang('de')">de</button>  
<p>{{rate}}</p>

Ts File - someComponent.ts

rate:string="productRate";
changeLang(lang){  
  this.translate.use(lang);
  this.traslate.get(this.rate).subscribe(res=>{this.rate = res;});
}  

Json file-en.json

{ "productRate": "Product Rate" }  

Json file-de.json

{ "productRate": "Produktpreis" }  

I know how to do it in template using pipe but unable to do it in ts.
I had referenced stack overflow but unable to get the result. Please help

Answer 1

From Docs

get(key: string|Array, interpolateParams?: Object): Observable: Gets the translated value of a key (or an array of keys) or the key if the value was not found

You have to inject TranslateService as a dependency and do it as,

constructor(private translate: TranslateService) {
    let foo:string = this.translate.get('productRate');
}