From 41f4bf5f3dd274c93738938b35eaf2c0a5428ea9 Mon Sep 17 00:00:00 2001
From: Austin Pray <austin@austinpray.com>
Date: Tue, 31 Oct 2017 14:51:38 -0700
Subject: [PATCH] Prefer fetch API over XHR

closes https://github.com/getsentry/raven-js/issues/930
---
 src/raven.js | 35 ++++++++++++++++++++++++++++++-----
 1 file changed, 30 insertions(+), 5 deletions(-)

diff --git a/src/raven.js b/src/raven.js
index 1d2e9008fc14..fcecb31514a6 100644
--- a/src/raven.js
+++ b/src/raven.js
@@ -1881,7 +1881,36 @@ Raven.prototype = {
     });
   },
 
+  /**
+   * @param {string} opts.url
+   * @param {Object} opts.auth
+   * @param {*} opts.data
+   * @param {Object} opts.options
+   * @callback opts.onSuccess
+   * @callback opts.onError
+   * @private
+   */
   _makeRequest: function(opts) {
+    // NOTE: auth is intentionally sent as part of query string (NOT as custom
+    //       HTTP header) so as to avoid preflight CORS requests
+    var url = opts.url + '?' + urlencode(opts.auth);
+
+    // https://github.com/Modernizr/Modernizr/blob/d5f881a4de0d5fc1af85921ce9c7dc3919c6d335/feature-detects/network/fetch.js
+    if ('fetch' in _window) {
+        return _window.fetch(url, {
+          method: 'POST',
+          body: stringify(opts.data)
+        }).then(function (response) {
+          if (!response.ok) {
+            return opts.onError && opts.onError(new Error('Sentry error code: ' + response.status))
+          }
+
+          opts.onSuccess && opts.onSuccess();
+        })["catch"](function () {
+          opts.onError && opts.onError(new Error('Sentry error code: network unavailable'));
+        })
+    }
+
     var request = _window.XMLHttpRequest && new _window.XMLHttpRequest();
     if (!request) return;
 
@@ -1890,8 +1919,6 @@ Raven.prototype = {
 
     if (!hasCORS) return;
 
-    var url = opts.url;
-
     if ('withCredentials' in request) {
       request.onreadystatechange = function() {
         if (request.readyState !== 4) {
@@ -1923,9 +1950,7 @@ Raven.prototype = {
       }
     }
 
-    // NOTE: auth is intentionally sent as part of query string (NOT as custom
-    //       HTTP header) so as to avoid preflight CORS requests
-    request.open('POST', url + '?' + urlencode(opts.auth));
+    request.open('POST', url);
     request.send(stringify(opts.data));
   },