dashboard/app: move coverage page js code to static file

Chrome  devtools allow to edit js code directly in browser.
This change will speed up further development.

dashboard/app/static/coverage.js

@@ -0,0 +1,28 @@
+// Copyright 2024 syzkaller project authors. All rights reserved.
+// Use of this source code is governed by Apache 2 LICENSE that can be found in the LICENSE file.
+
+initTogglers();
+
+// Initializes the file tree onClick collapse logic.
+function initTogglers(){
+  $(".caret").on("click", function() {
+    $(this).toggleClass("caret-down");
+    $(this).closest("li").find(".nested").first().toggleClass("active");
+  });
+}
+
+// This handler is called when user clicks on the coverage percentage.
+// It downloads the kernel file coverage html block and adjust page to show it.
+// "#file-content-prev" and "#file-content-curr" are the file content <div>s.
+// "#file-details-prev" and "#file-details-curr" are the corresponding <div>s used to show per-file details.
+function onShowFileContent(url) {
+  $.get(url, function(response) {
+    $("#file-content-prev").html($("#file-content-curr").html());
+    $("#file-content-curr").html(response);
+
+    $("#file-details-prev").html($("#file-details-curr").html());
+    // It looks hacky but costs nothing. Let's show all the url parameters as a source description.
+    details = url.split("?")[1].split("&");
+    $("#file-details-curr").html("Source information:\n" + details.join("\n"));
+  });
+}

pkg/cover/templates/heatmap.html

@@ -1,24 +1,12 @@
 {{ define "js" }}
 <script>
-  $(".caret").on("click", function() {
-    $(this).toggleClass("caret-down");
-    $(this).closest("li").find(".nested").first().toggleClass("active");
-  });
+    var domain = window.location.hostname;
+    var scriptUrl = 'https://' + domain + '/static/coverage.js';
 
-  function setContent(url, htmlContent) {
-    $("#file-content-prev").html($("#file-content-curr").html());
-    $("#file-details-prev").html($("#file-details-curr").html());
+    var script = document.createElement('script');
+    script.src = scriptUrl;
 
-    $("#file-content-curr").html(htmlContent);
-    details = url.split("?")[1].split("&");
-    $("#file-details-curr").html("Source information:\n" + details.join("\n"));
-  }
-
-  function onShowFileContent(url) {
-    $.get(url, function(response) {
-      setContent(url, response);
-    });
-  }
+    document.head.appendChild(script);
 </script>
 {{ end }}