Enable Save As Draft in Angular.

controller.ts

import debounce from 'lodash/debounce';
@Component({
  ...
})
export class MyController {
  public submission = {};
  ngAfterViewInit() {
    var currentSubmission = localStorage.getItem('currentSubmission-' + this.route.params.formId);
    if (currentSubmission) {
      this.submission = JSON.parse(currentSubmission);
      this.cdr.detectChanges();
    }
  }
  onChange(submission) {
    localStorage.setItem('currentSubmission-' + submission.form, JSON.stringify(submission));
  }
}

template.html

<formio [src]="formURL" (change)="onChange($event)" [submission]="submission" [renderOptions]="{
  saveDraft: true,
  saveDraftThrottle: 10000
}"></formio>