From 2f95d73fa8f01fc1201755f635bfdd34d841d04c Mon Sep 17 00:00:00 2001
From: Ben Lesh <ben@benlesh.com>
Date: Wed, 2 Sep 2020 15:38:24 -0500
Subject: [PATCH] refactor: Use readyState instead of the `done` boolean.

Addresses comments here: https://github.com/ReactiveX/rxjs/pull/5661\#discussion_r481786685
---
 src/internal/ajax/ajax.ts | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/src/internal/ajax/ajax.ts b/src/internal/ajax/ajax.ts
index e435d2faba..7f32bf38e9 100644
--- a/src/internal/ajax/ajax.ts
+++ b/src/internal/ajax/ajax.ts
@@ -271,8 +271,6 @@ export const ajax: AjaxCreationMethod = (() => {
 
 export function fromAjax<T>(config: AjaxConfig): Observable<AjaxResponse<T>> {
   return new Observable<AjaxResponse<T>>((destination) => {
-    let done = false;
-
     // Normalize the headers. We're going to make them all lowercase, since
     // Headers are case insenstive by design. This makes it easier to verify
     // that we aren't setting or sending duplicates.
@@ -368,7 +366,6 @@ export function fromAjax<T>(config: AjaxConfig): Observable<AjaxResponse<T>> {
           if (xhr.status < 400) {
             progressSubscriber?.complete?.();
 
-            done = true;
             let response: AjaxResponse<T>;
             try {
               // This can throw in IE, because we end up needing to do a JSON.parse
@@ -424,7 +421,7 @@ export function fromAjax<T>(config: AjaxConfig): Observable<AjaxResponse<T>> {
     }
 
     return () => {
-      if (!done && xhr) {
+      if (xhr && xhr.readyState !== 4 /*XHR done*/) {
         xhr.abort();
       }
     };