static/js/update: Handle no drift

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

1 files changed, 13 insertions, 4 deletions

diff --git a/static/js/update.ts b/static/js/update.ts
index cee1c92..94a509a 100644
--- a/static/js/update.ts
+++ b/static/js/update.ts
@@ -1,5 +1,5 @@
 (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) {
@@ -15,15 +15,24 @@
 
   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]");
+      const anchor = indicator.cloneNode();
+
+      function reset() {
+        indicator.href = anchor.href;
+        indicator.setAttribute("id", anchor.id);
+        indicator.dataset.update = anchor.dataset.update;
+      }
+
+      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";