Refactored version-switcher.js

- Simplified code
- Stopped using jQuery
- Moved refactored code to `djangoproject.js`

This patch should bring no user-facing changes.

Refs #1827

djangoproject/static/js/djangoproject.js

@@ -4,3 +4,10 @@ document.querySelectorAll('.doc-switcher li.current').forEach(function (el) {
     this.parentElement.classList.toggle('open');
   });
 });
+
+// Propagate the current fragment identifier when switching docs versions
+document.querySelectorAll('#doc-versions a').forEach(function (el) {
+  el.addEventListener('click', function () {
+    this.href = this.href.split('#')[0] + window.location.hash;
+  });
+});

djangoproject/static/js/main.js

@@ -19,10 +19,6 @@ define(function () {
     mods.push('mod/list-collapsing');
   }
 
-  if (hasClass('version-switcher')) {
-    mods.push('mod/version-switcher');
-  }
-
   if (hasClass('doc-floating-warning')) {
     mods.push('mod/floating-warning');
   }

djangoproject/templates/base.html

@@ -154,7 +154,6 @@
           "mod/list-collapsing": extless("{% static 'js/mod/list-collapsing.js' %}"),
           "mod/list-feature": extless("{% static 'js/mod/list-feature.js' %}"),
           "mod/mobile-menu": extless("{% static 'js/mod/mobile-menu.js' %}"),
-          "mod/version-switcher": extless("{% static 'js/mod/version-switcher.js' %}"),
           "mod/search-key": extless("{% static 'js/mod/search-key.js' %}"),
           "mod/stripe-change-card": extless("{% static 'js/mod/stripe-change-card.js' %}"),
           "mod/switch-dark-mode": extless("{% static 'js/mod/switch-dark-mode.js' %}"),