Angular 4/5 HttpClient: Argument of type string is not assignable to 'body'

Question

The Angular docs say:

The response body doesn\'t return all the data you may need. Sometimes servers return special headers or status codes to indic

Answer 1

import { HttpHeaders, HttpParams } from '@angular/common/http';
export interface IRequestOptions {
    headers?: HttpHeaders | { [header: string]: string | string[]; };
    observe: "response"; 
    params?: HttpParams | { [param: string]: string | string[]; };
    reportProgress?: boolean; 
    responseType?: "json";
    withCredentials?: boolean; 
}