Ensure admin tab events are handled on page load

The `shown.bs.tab` event was being bound after showTab() was already
called, so on page load, the tabs weren't being updated correctly.

CHANGELOG.txt

@@ -36,6 +36,7 @@ Changelog
  * Fix: Add handling of invalid inline styles submitted to `RichText` so `ConfigException` is not thrown (Alex Tomkins)
  * Fix: Ensure comment notifications dropdown handles longer translations without overflowing content (Krzysztof Jeziorny)
  * Fix: Set `default_auto_field` in `postgres_search` `AppConfig` (Nick Moreton)
+ * Fix: Ensure admin tab JS events are handled on page load (Andrew Stone)
 
 
 2.14.1 (12.08.2021)

client/src/entrypoints/admin/core.js

@@ -295,6 +295,16 @@ $(() => {
     $(this).closest('li').removeClass('focused');
   });
 
+  /* Functions that need to run/rerun when active tabs are changed */
+  $(document).on('shown.bs.tab', () => {
+    // Resize autosize textareas
+    // eslint-disable-next-line func-names
+    $('textarea[data-autosize-on]').each(function () {
+      // eslint-disable-next-line no-undef
+      autosize.update($(this).get());
+    });
+  });
+
   /* tabs */
   const showTab = (tabButtonElem) => {
     $(tabButtonElem).tab('show');
@@ -419,16 +429,6 @@ $(() => {
     };
   }
 
-  /* Functions that need to run/rerun when active tabs are changed */
-  $(document).on('shown.bs.tab', () => {
-    // Resize autosize textareas
-    // eslint-disable-next-line func-names
-    $('textarea[data-autosize-on]').each(function () {
-      // eslint-disable-next-line no-undef
-      autosize.update($(this).get());
-    });
-  });
-
   /* Debounce submission of long-running forms and add spinner to give sense of activity */
   // eslint-disable-next-line func-names
   $(document).on('click', 'button.button-longrunning', function () {

docs/releases/2.15.rst

@@ -51,6 +51,7 @@ Bug fixes
  * Add handling of invalid inline styles submitted to ``RichText`` so ``ConfigException`` is not thrown (Alex Tomkins)
  * Ensure comment notifications dropdown handles longer translations without overflowing content (Krzysztof Jeziorny)
  * Set ``default_auto_field`` in ``postgres_search`` ``AppConfig`` (Nick Moreton)
+ * Ensure admin tab JS events are handled on page load (Andrew Stone)
 
 Upgrade considerations
 ======================