static/js/update: Handle no drift

Some browsers can't read headers. Prepare _self
and add reset state

1 files changed, 6 insertions, 4 deletions

diff --git a/assets/js/index.js b/assets/js/index.js
index 83d3943..ef35f63 100644
--- a/assets/js/index.js
+++ b/assets/js/index.js
@@ -93,7 +93,7 @@
     });
 })();
 (function() {
-    function check(url, method, callback) {
+    function fetch(url, method, callback) {
         const http = new XMLHttpRequest();
         http.onreadystatechange = function() {
             if (http.readyState === 4 && http.status === 200) {
@@ -108,14 +108,16 @@
     }
     function update() {
         const url = self.location.href.split("#")[0].split("?")[0];
-        check(url, "HEAD", function(request) {
+        fetch(url, "HEAD", function(request) {
             const local = document.querySelector('meta[name="last-modified"]').content;
             const remote = request.getResponseHeader("last-modified") || '';
             const modified = Date.parse(document.lastModified) !== Date.parse(remote);
             const drift = Date.parse(remote || local) - Date.parse(local);
+            let indicator = document.querySelector("a[data-update]");
+            indicator.cloneNode();
+            if (drift === 0) return;
             if (remote && modified) {
-                const indicator = document.querySelector("a[data-update]");
-                check(url, "GET");
+                fetch(url, "GET");
                 indicator.href = url;
                 indicator.removeAttribute("id");
                 indicator.dataset.update = "refresh";