open filters on load if not empty or 'all'

make-pages/GalleryPage.hs

@@ -44,7 +44,7 @@ make' (GalleryInfo {title, prefix, filters, hidden}) infos = [b|@0
     </header>
 
     <nav id=filters>
-      <details>
+      <details id=filters-details>
         <summary><h2>filters</h2></summary>
         <div>
           <h3>show only</h3>

script/gallery.js

@@ -86,7 +86,7 @@ function makeFragment() {
   }
 }
 
-function useFragment() {
+function useFragment(firstLoad) {
   let frag = document.location.hash.replace(/^#/, '');
 
   if (frag == 'all') {
@@ -94,6 +94,7 @@ function useFragment() {
   } else if (frag) {
     let set = new Set(frag.split(';'));
     allBoxes.forEach(b => b.checked = set.has(b.id));
+    if (firstLoad) document.getElementById('filters-details').open = true;
   } else {
     resetForm();
   }
@@ -108,8 +109,8 @@ function setup() {
   document.getElementById('clear').addEventListener('click', clear);
   document.getElementById('reset').addEventListener('click', reset);
 
-  window.addEventListener('popstate', useFragment);
-  useFragment();
+  window.addEventListener('popstate', () => useFragment(false));
+  useFragment(true);
 }
 
 window.addEventListener('load', setup);