Emit errors when request is aborted

docs/api.md

@@ -350,6 +350,9 @@ interface HttpRequest {
     // - in browsers: a TypedArray, a DataView a Blob, or null.
     // - in  Node.js: a Buffer, a ReadableStream, or null.
     send(body: any): Promise<HttpResponse>;
+
+    // Aborts the request if it's currently in progress. If so, `send` should reject
+    // with an error of type DOMException, with name AbortError.
     abort(): Promise<void>;
 
     // Return an environment specific object, e.g. the XMLHttpRequest object in browsers.

lib/browser/FetchHttpStack.ts

@@ -68,6 +68,7 @@ class FetchRequest implements HttpRequest {
   }
 
   abort(): Promise<void> {
+    // Note: When abort() is called, the fetch() promise rejects with an Error of type DOMException, with name AbortError.
     this._controller.abort()
     return Promise.resolve()
   }

lib/browser/XHRHttpStack.ts

@@ -81,11 +81,16 @@ class XHRRequest implements HttpRequest {
         reject(err)
       }
 
+      this._xhr.onabort = () => {
+        reject(new DOMException('Request was aborted', 'AbortError'))
+      }
+
       this._xhr.send(body)
     })
   }
 
   abort(): Promise<void> {
+    // Note: Calling abort() triggers the `abort` event, but no `error` event.
     this._xhr.abort()
     return Promise.resolve()
   }

lib/node/NodeHttpStack.ts

@@ -146,7 +146,9 @@ class Request implements HttpRequest {
   }
 
   abort() {
-    if (this._request != null) this._request.abort()
+    // Note: The destroy() method will trigger an `error` event with the provided error.
+    if (this._request != null)
+      this._request.destroy(new DOMException('Request was aborted', 'AbortError'))
     return Promise.resolve()
   }
 

lib/options.ts

@@ -155,6 +155,9 @@ export interface HttpRequest {
   setProgressHandler(handler: HttpProgressHandler): void
   // TODO: Should this be something like { value: unknown, size: number }?
   send(body?: SliceType): Promise<HttpResponse>
+
+  // Aborts the request if it's currently in progress. If so, `send` should reject
+  // with an error of type DOMException, with name AbortError.
   abort(): Promise<void>
 
   // Return an environment specific object, e.g. the XMLHttpRequest object in browsers.