Ask server to respond with clear-site-data when pressing the reset cache button

Author: GarboMuffin

src/playground/index.ejs

@@ -157,8 +157,12 @@
         splashReset.onclick = function () {
           splashReset.disabled = true;
           function hardRefresh() {
-            var search = location.search.replace(/[?&]nocache=\d+/, '');
-            location.replace(location.pathname + search + (search ? '&' : '?') + 'nocache=' + Math.floor(Math.random() * 100000));
+            var search = location.search.replace(/[?&]nocache=[\d.]+(?=$|&)/, '');
+            // This is a functional cookie used so that we respond with Clear-Site-Data just once. No tracking.
+            // Can't use nocache parameter to trigger this because people might accidentally bookmark that, and
+            // then we would be clearing their cache on every visit.
+            document.cookie = 'tw_clear_cache_once=1; max-age=60; path=/; samesite=strict; secure';
+            location.replace(location.pathname + search + (search ? '&' : '?') + 'nocache=' + Math.floor(Math.random() * 10000000));
           }
           if ('serviceWorker' in navigator) {
             setTimeout(hardRefresh, 5000);