manipulate data fetched from remote api angular 2 - loops

Question

Im receiving data from the Marvel api and use ngFor to display the data.
Before displaying the data I need to make some changes to it.
If the name doesn't exist or the description is empty I want to show a message.
Where is the best place to manipulate data and how can I do this?
I tried something like this in my comic view after the subscribe but it didnt work.
If (stuff.data.results['0'].title == ''){
stuff.data.results['0'].title == 'try gain'}
my service.ts
getComics(searchterm): Observable<any> {
const search: URLSearchParams = new URLSearchParams();
search.set('titleStartsWith',searchterm);
search.set('ts', '1'); // time stamp
search.set('apikey', 'key');
search.set('hash', 'key');
let obs: Observable<any> = this.http
.get(ComicService.BASE_URL, new RequestOptions({search}))
.map( (res) => res.json());
console.log("obj " + obs)
return obs;
}
my comic-view.ts
searchComics(event): boolean {
this.error = 'fout'
this._comicService.getComics(this.searchterm)
.subscribe(
stuff => {
this.stuff = stuff; console.log('title: ' + stuff.data.results['0'].title + ' description:' +
stuff.data.results['0'].description);
},
error => { this.error = error; }
);
return false;
}
comis.html
<ul>
<li *ngFor=" let x of stuff?.data?.results ">
<label> Title:</label> {{x.title}}
<br>
<label> description: </label> {{x.description}}
<br>
</li>
</ul>