How to use JSON file from HTML input in Angular 8?

In my current Angular 8 project I have two JSON files which should be connected to one JSON array. The new file should then be exported.

After googling for a long time I didn't find a solution how to use the two JSON files, which I call up via two HTML inputs, so that I can combine both files in the Angular Component to form a JSON array with input from both JSON files.

My current code:

JsonConverterComponent.html

<div class="form-group">
   <label for="Json1">Json 1</label>
      <input [(ngModel)]="json1" type="file" id="Json1" required>
</div>
<div class="form-group">
   <label for="Json2">Json 2</label>
      <input [(ngModel)]="json2" type="file" id="Json2" required>
</div>
<button [buttonLabel]="buttonNameJson" [disableCheck]="!json1 || !json2" (click)="combineJSON()"></button>

JsonConverterComponent.TS

export class JsonConverterComponent implements OnInit {

  constructor(private http: HttpClient) { }

  ngOnInit() {
  }

  buttonNameJson = "Combine JSON";
  json1: File;
  json2: File;
  test: File;

  one = this.json1;
  two = this.json2;

  public combineJSON() {
    this.test = this.one;
    console.log(this.test);
  }
}

If I just want to call up the content of one of the two imported JSON files, I always get the error "undefined".

What do I have to do so that I can use the individual JSON in JsonConverterComponent.ts?

The ngModel directive can't be used on a input of type file, you have to react on the change event like this:

<input (change)="onFileChange($event)" type="file" id="Json1" required>

<input (change)="onFileChange($event)" type="file" id="Json2" required>

Then in the TypeScript file:

onFileChange(event){
    const fileToLoad = event.target.files[0];
    const fileReader = new FileReader();
    fileReader.onload = function(fileLoadedEvent){
        const textFromFileLoaded = fileLoadedEvent.target.result;
        const json = JSON.parse(textFromFileLoaded);
        console.log(json);
    };
    fileReader.readAsText(fileToLoad, "UTF-8");
}