Add keepalive caveat

Closes #780
JakeChampion · Jul 10, 2020 · 259dc6a · 259dc6a
1 parent b65ed60
commit 259dc6a
Showing 1 changed file with 2 additions and 0 deletions.
diff --git a/README.md b/README.md
@@ -192,6 +192,8 @@ fetch('/avatars', {
 * Not all Fetch standard options are supported in this polyfill. For instance,
   [`redirect`](#redirect-modes) and
   [`cache`](https://github.github.io/fetch/#caveats) directives are ignored.
+
+* `keepalive` is not supported because it would involve making a synchronous XHR, which is something this project is not willing to do. See [issue #700](https://github.com/github/fetch/issues/700#issuecomment-484188326) for more information.
 
 #### Handling HTTP error statuses