property does not exist on type object code example

Example 1: Property 'of' does not exist on type 'typeof Observable'.

import { of } from 'rxjs';

Example 2: Property 'on' does not exist on type 'HTMLElement'.

To prevent this error you can write:

var plotDiv: any = document.getElementById('myDiv');
plotDiv.on('plotly_relayout', ...
document.getElementById('myDiv') return HTMLElement. This type doesn't contain method
on because this method is added within plotly-latest.min.js. So in order to silence
the typescript warning you can explicity say compile not to check types for plotDiv

Another way is create type definition like:

interface PlotHTMLElement extends HTMLElement  {
  on(eventName: string, handler: Function): void;
}

var plotDiv  = <PlotHTMLElement>document.getElementById('myDiv')
plotDiv.on('plotly_relayout', function() {

});

Example 3: Property 'find' does not exist on type NodeListOf

const elements = Array.from(document.querySelectorAll('.selector'));
elements.forEach((...) => {});

Example 4: property 'do' does not exist on type 'observable>'. angular 9

import { tap } from 'rxjs/operators';

const TOKEN_HEADER_KEY = 'Authorization';

@Injectable()
export class Interceptor implements HttpInterceptor {

  constructor(private token: TokenStorage, private router: Router) { }

  intercept(req: HttpRequest<any>, next: HttpHandler):
    Observable<HttpSentEvent | HttpHeaderResponse | HttpProgressEvent | HttpResponse<any> | HttpUserEvent<any>> {
    let authReq = req;
    if (this.token.getToken() != null) {
      authReq = req.clone({ headers: req.headers.set(TOKEN_HEADER_KEY, 'Bearer ' + this.token.getToken())});
    }
    return next.handle(authReq).pipe(tap(
        (err: any) => {
          if (err instanceof HttpErrorResponse) {
            console.log(err);
            console.log('req url :: ' + req.url);
            if (err.status === 401) {
              this.router.navigate(['user']);
            }
          }
        }
      ));
  }

}

Example 5: Property 'users' does not exist on type 'UsersDTO[]'. 29 if (saveUser.users.length < 1) {

// for JSON:
const { value } = ctx.request.body({ type: "json" });
const { text } = await value;

// for FormData:
const { value } = ctx.request.body({ type: "form-data" });
const formData = await value.read();
const { text } = formData.fields;