feat(AjaxResponse): add stricter type (AjaxResponseType)

src/internal/ajax/AjaxResponse.ts

@@ -1,4 +1,4 @@
-import { AjaxRequest } from './types';
+import { AjaxRequest, AjaxResponseType } from './types';
 import { getXHRResponse } from './getXHRResponse';
 
 /**
@@ -90,7 +90,7 @@ export class AjaxResponse<T> {
      * `download_load` is the type of event when download has finished and the
      * response is available.
      */
-    public readonly type: string = 'download_load'
+    public readonly type: AjaxResponseType = 'download_load'
   ) {
     const { status, responseType } = xhr;
     this.status = status ?? 0;

src/internal/ajax/ajax.ts

@@ -1,6 +1,6 @@
 import { map } from '../operators/map';
 import { Observable } from '../Observable';
-import { AjaxConfig, AjaxRequest, AjaxDirection } from './types';
+import { AjaxConfig, AjaxRequest, AjaxDirection, AjaxResponseType, ProgressEventType } from './types';
 import { AjaxResponse } from './AjaxResponse';
 import { AjaxTimeoutError, AjaxError } from './errors';
 
@@ -414,7 +414,7 @@ export function fromAjax<T>(config: AjaxConfig): Observable<AjaxResponse<T>> {
        * @param event the actual event object.
        */
       const createResponse = (direction: AjaxDirection, event: ProgressEvent) =>
-        new AjaxResponse<T>(event, xhr, _request, `${direction}_${event.type}`);
+        new AjaxResponse<T>(event, xhr, _request, `${direction}_${event.type as ProgressEventType}` as const);
 
       /**
        * Wires up an event handler that emits a Response object to the consumer, used for

src/internal/ajax/types.ts

@@ -7,6 +7,10 @@ import { PartialObserver } from '../types';
  */
 export type AjaxDirection = 'upload' | 'download';
 
+export type ProgressEventType = 'loadstart' | 'progress' | 'load';
+
+export type AjaxResponseType = `${AjaxDirection}_${ProgressEventType}`;
+
 /**
  * The object containing values RxJS used to make the HTTP request.
  *