Angular HttpClient append headers to HttpHeaders [duplicate]
HttpHeaders.append returns a clone of the headers with the value appened, it does not update the object. You need to set the returned value to the headers.
angular/packages/common/http/src/headers.ts
append(name: string, value: string|string[]): HttpHeaders { return this.clone({name, value, op: 'a'}); } So to append the headers you do this.
let headers: HttpHeaders = new HttpHeaders();headers = headers.append('Content-Type', 'application/json');headers = headers.append('x-corralation-id', '12345');and boom!