ref: Remove keepalive:true as a default and document payload size

Author: kamilogorek

docs/config.rst

@@ -327,13 +327,15 @@ Those configuration options are documented below:
 
     ``fetch()`` init parameters (https://developer.mozilla.org/en-US/docs/Web/API/WindowOrWorkerGlobalScope/fetch#Parameters).
 
+    Setting ``keepalive: true`` parameter will allow SDK to send events in ``unload`` and ``beforeunload`` handlers.
+    However, it'll also restrict the size of a single event to 64kB, per `fetch specification <https://fetch.spec.whatwg.org/#http-network-or-cache-fetch`__ (point 8.5).
+
     Defaults:
 
     .. code-block:: javascript
 
         {
             method: 'POST',
-            keepalive: true,
             referrerPolicy: 'origin'
         }
 

docs/usage.rst

@@ -132,7 +132,9 @@ functions all allow passing additional data to be tagged onto the error.
 
         Raven.wrap({
           tags: {git_commit: 'c0deb10c4'}
-        }, function () { /* ... */ });
+        }, function () {
+          // ...
+        });
 
         // NOTE: Raven.wrap and Raven.context accept options as first argument
 
@@ -163,7 +165,9 @@ functions all allow passing additional data to be tagged onto the error.
 
         Raven.context({
           extra: {planet: {name: 'Earth'}}
-        }, function () { /* ... */ });
+        }, function () {
+          // ...
+        });
 
         // NOTE: Raven.wrap and Raven.context accept options as first argument
 
@@ -186,6 +190,10 @@ functions all allow passing additional data to be tagged onto the error.
         Raven.setExtraContext();            // Clear all extra data from the context.
         Raven.setExtraContext(extra);       // Add back the extra data that you want to keep.
 
+**Be aware of maximal payload size** - There are times, when you want to send a whole application state as an extra data.
+This can be quite a large object, which can easily weigh more than 200kB, which is currently maximamal payload size of a single event sent to Sentry.
+When this happens, you'll get an ``HTTP Error 413 Payload Too Large`` as the server response or (when ``keepalive: true`` is set as ``fetch`` parameter) request will stay in ``pending`` state forever (eg. in Chrome).
+
 .. _raven-js-recording-breadcrumbs:
 
 Recording Breadcrumbs

packages/raven-js/src/raven.js

@@ -98,7 +98,6 @@ function Raven() {
   };
   this._fetchDefaults = {
     method: 'POST',
-    keepalive: true,
     // Despite all stars in the sky saying that Edge supports old draft syntax, aka 'never', 'always', 'origin' and 'default
     // https://caniuse.com/#feat=referrer-policy
     // It doesn't. And it throw exception instead of ignoring this parameter...

packages/raven-js/test/raven.test.js

@@ -1870,7 +1870,6 @@ describe('globals', function() {
           assert.deepEqual(window.fetch.lastCall.args, [
             'http://localhost/?a=1&b=2',
             {
-              keepalive: true,
               referrerPolicy: supportsReferrerPolicy() ? 'origin' : '',
               method: 'POST',
               body: '{"foo":"bar"}'