From 5e3830337764b07bb50a33122dc2cef793528e64 Mon Sep 17 00:00:00 2001
From: David Fowler <davidfowl@gmail.com>
Date: Tue, 3 Apr 2018 15:53:16 -0700
Subject: [PATCH] Use xhr.onreadystatechange instead of xhr.onload (#1838)

---
 clients/ts/signalr/src/HttpClient.ts | 23 +++++++++++++++--------
 1 file changed, 15 insertions(+), 8 deletions(-)

diff --git a/clients/ts/signalr/src/HttpClient.ts b/clients/ts/signalr/src/HttpClient.ts
index 2be9686264..16808e99ee 100644
--- a/clients/ts/signalr/src/HttpClient.ts
+++ b/clients/ts/signalr/src/HttpClient.ts
@@ -84,15 +84,22 @@ export class DefaultHttpClient extends HttpClient {
                 xhr.timeout = request.timeout;
             }
 
-            xhr.onload = () => {
-                if (request.abortSignal) {
-                    request.abortSignal.onabort = null;
-                }
+            xhr.onreadystatechange = () => {
+                if (xhr.readyState === 4) {
+                    if (request.abortSignal) {
+                        request.abortSignal.onabort = null;
+                    }
 
-                if (xhr.status >= 200 && xhr.status < 300) {
-                    resolve(new HttpResponse(xhr.status, xhr.statusText, xhr.response || xhr.responseText));
-                } else {
-                    reject(new HttpError(xhr.statusText, xhr.status));
+                    // Some browsers report xhr.status == 0 when the
+                    // response has been cut off or there's been a TCP FIN.
+                    // Treat it like a 200 with no response.
+                    if (xhr.status === 0) {
+                        resolve(new HttpResponse(200, null, null));
+                    } else if (xhr.status >= 200 && xhr.status < 300) {
+                        resolve(new HttpResponse(xhr.status, xhr.statusText, xhr.response || xhr.responseText));
+                    } else {
+                        reject(new HttpError(xhr.statusText, xhr.status));
+                    }
                 }
             };