Merge "resourceloader: Restore the comment about <script> vs XHR loading"

diff --git a/resources/src/startup/mediawiki.js b/resources/src/startup/mediawiki.js
index b5ba6a6..65cf316 100644 (file)
--- a/resources/src/startup/mediawiki.js
+++ b/resources/src/startup/mediawiki.js
@@ -1102,6 +1102,12 @@
                         * @param {Function} [callback] Callback to run after request resolution
                         */
                        function addScript( src, callback ) {
+                               // Use a <script> element rather than XHR. Using XHR changes the request
+                               // headers (potentially missing a cache hit), and reduces caching in general
+                               // since browsers cache XHR much less (if at all). And XHR means we retrieve
+                               // text, so we'd need to eval, which then messes up line numbers.
+                               // The drawback is that <script> does not offer progress events, feedback is
+                               // only given after downloading, parsing, and execution have completed.
                                var script = document.createElement( 'script' );
                                script.src = src;
                                script.onload = script.onerror = function () {