Fix copy logic

web/static/app.js

@@ -12,15 +12,36 @@
       var target = document.getElementById(button.dataset.copy);
       if (!target) return;
       button.hidden = false;
+
+      var label = button.textContent, timer;
+      function say(word) {
+        button.textContent = word;
+        clearTimeout(timer);
+        timer = setTimeout(function () { button.textContent = label; }, 1500);
+      }
+
+      // Copying the selection needs neither a permission nor a secure context,
+      // so it answers for both of the ways the clipboard API can let us down:
+      // missing entirely (this service is reached over plain HTTP as well as
+      // HTTPS, and the API exists only on the secure side) or present and
+      // refusing (an unfocused document, a permissions policy). If even that
+      // fails, the text is selected either way, so say what to press.
+      function copySelection() {
+        var ok = false;
+        try { ok = document.execCommand('copy'); } catch (e) { /* ok stays false */ }
+        say(ok ? 'Copied' : 'Press Ctrl-C');
+      }
+
       button.addEventListener('click', function () {
         target.select();
-        var done = function () {
-          var was = button.textContent;
-          button.textContent = 'Copied';
-          setTimeout(function () { button.textContent = was; }, 1500);
-        };
-        if (navigator.clipboard) navigator.clipboard.writeText(target.value).then(done, function () {});
-        else { document.execCommand('copy'); done(); }
+        target.setSelectionRange(0, target.value.length); // iOS ignores select()
+        if (navigator.clipboard && navigator.clipboard.writeText) {
+          navigator.clipboard.writeText(target.value).then(function () {
+            say('Copied');
+          }, copySelection);
+        } else {
+          copySelection();
+        }
       });
     });
   }