Fix colours of table rows and JS exception on sig_refs being null.

webassets/js/alerts.js

@@ -51,7 +51,7 @@ function updateTable() {
     var showRef = $("#tableShowRef")[0].checked;
 
     // Populate table with headers
-    let table = $('<table class="table table-striped-custom table-hover">').append('<thead><tr class="table-primary"></tr></thead><tbody></tbody>');
+    let table = $('<table class="table table-hover">').append('<thead><tr class="table-primary"></tr></thead><tbody></tbody>');
     if (showStartTime) {
         table.find('thead tr').append(`<th>${useLocalTime ? "Start&nbsp;(Local)" : "Start&nbsp;UTC"}</th>`);
     }
@@ -107,10 +107,18 @@ function updateTable() {
 
 // Add a row to tbody for each alert in the provided list
 function addAlertRowsToTable(tbody, alerts) {
+    var count = 0;
     alerts.forEach(a => {
         // Create row
         let $tr = $('<tr>');
 
+        // Apply striping to the table. We can't just use Bootstrap's table-striped class because we have all sorts of
+        // extra faff to deal with, like the mobile view having extra rows, and the On Now / Next 24h / Later banners
+        // which cause the table-striped colouring to go awry.
+        if (count % 2 == 1) {
+            $tr.addClass("table-active");
+        }
+
         // Use local time instead of UTC?
         var useLocalTime = $("#timeZone")[0].value == "local";
 
@@ -236,6 +244,9 @@ function addAlertRowsToTable(tbody, alerts) {
 
         // Second row for mobile view only, containing source, ref, freqs/modes & comment
         $tr2 = $("<tr class='hidenotonmobile'>");
+        if (count % 2 == 1) {
+            $tr2.addClass("table-active");
+        }
         $td2 = $("<td colspan='100'>");
         if (showSource) {
             $td2.append(`<span class='icon-wrapper'><i class='fa-solid fa-${a["icon"]}'></i></span> `);
@@ -251,6 +262,8 @@ function addAlertRowsToTable(tbody, alerts) {
         }
         $tr2.append($td2);
         tbody.append($tr2);
+
+        count++;
     });
 }