Dropdown menu alignment fixes

js/src/dropdown.js

@@ -156,7 +156,9 @@ class Dropdown extends BaseComponent {
     }
 
     // Totally disable Popper for Dropdowns in Navbar
-    if (!this._inNavbar) {
+    if (this._inNavbar) {
+      Manipulator.setDataAttribute(this._menu, 'popper', 'none')
+    } else {
       if (typeof Popper === 'undefined') {
         throw new TypeError('Bootstrap\'s dropdowns require Popper (https://popper.js.org)')
       }
@@ -176,7 +178,14 @@ class Dropdown extends BaseComponent {
         referenceElement = this._config.reference
       }
 
-      this._popper = Popper.createPopper(referenceElement, this._menu, this._getPopperConfig())
+      const popperConfig = this._getPopperConfig()
+      const isDisplayStatic = popperConfig.modifiers.find(modifier => modifier.name === 'applyStyles' && modifier.enabled === false)
+
+      if (isDisplayStatic) {
+        Manipulator.setDataAttribute(this._menu, 'popper', 'static')
+      }
+
+      this._popper = Popper.createPopper(referenceElement, this._menu, popperConfig)
     }
 
     // If this is a touch-enabled device we add extra
@@ -218,6 +227,7 @@ class Dropdown extends BaseComponent {
 
     this._menu.classList.toggle(CLASS_NAME_SHOW)
     this._element.classList.toggle(CLASS_NAME_SHOW)
+    Manipulator.removeDataAttribute(this._menu, 'popper')
     EventHandler.trigger(this._element, EVENT_HIDDEN, relatedTarget)
   }
 
@@ -421,6 +431,7 @@ class Dropdown extends BaseComponent {
 
       dropdownMenu.classList.remove(CLASS_NAME_SHOW)
       toggles[i].classList.remove(CLASS_NAME_SHOW)
+      Manipulator.removeDataAttribute(dropdownMenu, 'popper')
       EventHandler.trigger(toggles[i], EVENT_HIDDEN, relatedTarget)
     }
   }

js/tests/unit/dropdown.spec.js

@@ -1006,13 +1006,44 @@ describe('Dropdown', () => {
 
       const btnDropdown = fixtureEl.querySelector('[data-bs-toggle="dropdown"]')
       const dropdownMenu = fixtureEl.querySelector('.dropdown-menu')
+      const dropdown = new Dropdown(btnDropdown)
 
       btnDropdown.addEventListener('shown.bs.dropdown', () => {
+        expect(dropdown._popper).toBeNull()
         expect(dropdownMenu.getAttribute('style')).toEqual(null, 'no inline style applied by Popper')
         done()
       })
 
-      btnDropdown.click()
+      dropdown.show()
+    })
+
+    it('should manage bs attribute `data-bs-popper`="none" when dropdown is in navbar', done => {
+      fixtureEl.innerHTML = [
+        '<nav class="navbar navbar-expand-md navbar-light bg-light">',
+        '  <div class="dropdown">',
+        '    <button class="btn dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">Dropdown</button>',
+        '    <div class="dropdown-menu">',
+        '      <a class="dropdown-item" href="#">Secondary link</a>',
+        '    </div>',
+        '  </div>',
+        '</nav>'
+      ].join('')
+
+      const btnDropdown = fixtureEl.querySelector('[data-bs-toggle="dropdown"]')
+      const dropdownMenu = fixtureEl.querySelector('.dropdown-menu')
+      const dropdown = new Dropdown(btnDropdown)
+
+      btnDropdown.addEventListener('shown.bs.dropdown', () => {
+        expect(dropdownMenu.getAttribute('data-bs-popper')).toEqual('none')
+        dropdown.hide()
+      })
+
+      btnDropdown.addEventListener('hidden.bs.dropdown', () => {
+        expect(dropdownMenu.getAttribute('data-bs-popper')).toBeNull()
+        done()
+      })
+
+      dropdown.show()
     })
 
     it('should not use Popper if display set to static', done => {
@@ -1037,6 +1068,33 @@ describe('Dropdown', () => {
       btnDropdown.click()
     })
 
+    it('should manage bs attribute `data-bs-popper`="static" when display set to static', done => {
+      fixtureEl.innerHTML = [
+        '<div class="dropdown">',
+        '  <button class="btn dropdown-toggle" data-bs-toggle="dropdown" data-bs-display="static">Dropdown</button>',
+        '  <div class="dropdown-menu">',
+        '    <a class="dropdown-item" href="#">Secondary link</a>',
+        '  </div>',
+        '</div>'
+      ].join('')
+
+      const btnDropdown = fixtureEl.querySelector('[data-bs-toggle="dropdown"]')
+      const dropdownMenu = fixtureEl.querySelector('.dropdown-menu')
+      const dropdown = new Dropdown(btnDropdown)
+
+      btnDropdown.addEventListener('shown.bs.dropdown', () => {
+        expect(dropdownMenu.getAttribute('data-bs-popper')).toEqual('static')
+        dropdown.hide()
+      })
+
+      btnDropdown.addEventListener('hidden.bs.dropdown', () => {
+        expect(dropdownMenu.getAttribute('data-bs-popper')).toBeNull()
+        done()
+      })
+
+      dropdown.show()
+    })
+
     it('should remove "show" class if tabbing outside of menu', done => {
       fixtureEl.innerHTML = [
         '<div class="dropdown">',

scss/_dropdown.scss

@@ -17,7 +17,6 @@
 .dropdown-menu {
   position: absolute;
   top: 100%;
-  left: 0;
   z-index: $zindex-dropdown;
   display: none; // none by default, but block on "open" of the menu
   min-width: $dropdown-min-width;
@@ -33,9 +32,8 @@
   @include border-radius($dropdown-border-radius);
   @include box-shadow($dropdown-box-shadow);
 
-  // Reset positioning when positioned with Popper
-  &[style] {
-    right: auto#{"/* rtl:ignore */"} !important; // stylelint-disable-line declaration-no-important
+  &[data-bs-popper] {
+    left: 0;
   }
 }
 
@@ -49,14 +47,20 @@
 
     .dropdown-menu#{$infix}-start {
       --bs-position: start;
-      right: auto #{"/* rtl:ignore */"};
-      left: 0 #{"/* rtl:ignore */"};
+
+      &[data-bs-popper] {
+        right: auto #{"/* rtl:ignore */"};
+        left: 0 #{"/* rtl:ignore */"};
+      }
     }
 
     .dropdown-menu#{$infix}-end {
       --bs-position: end;
-      right: 0 #{"/* rtl:ignore */"};
-      left: auto #{"/* rtl:ignore */"};
+
+      &[data-bs-popper] {
+        right: 0 #{"/* rtl:ignore */"};
+        left: auto #{"/* rtl:ignore */"};
+      }
     }
   }
 }

site/content/docs/5.0/components/dropdowns.md

@@ -30,10 +30,10 @@ Any single `.btn` can be turned into a dropdown toggle with some markup changes.
 
 {{< example >}}
 <div class="dropdown">
-  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-bs-toggle="dropdown" aria-expanded="false">
+  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton1" data-bs-toggle="dropdown" aria-expanded="false">
     Dropdown button
   </button>
-  <ul class="dropdown-menu" aria-labelledby="dropdownMenuButton">
+  <ul class="dropdown-menu" aria-labelledby="dropdownMenuButton1">
     <li><a class="dropdown-item" href="#">Action</a></li>
     <li><a class="dropdown-item" href="#">Another action</a></li>
     <li><a class="dropdown-item" href="#">Something else here</a></li>
@@ -635,10 +635,12 @@ Add `.disabled` to items in the dropdown to **style them as disabled**.
 
 ## Menu alignment
 
-By default, a dropdown menu is automatically positioned 100% from the top and along the left side of its parent. Add `.dropdown-menu-end` to a `.dropdown-menu` to right align the dropdown menu. Directions are mirrored when using Bootstrap in RTL, meaning `.dropdown-menu-end` will appear on the left side.
+By default, a dropdown menu is automatically positioned 100% from the top and along the left side of its parent. You can change this with the directional `.drop*` classes, but you can also control them with additional modifier classes.
+
+Add `.dropdown-menu-end` to a `.dropdown-menu` to right align the dropdown menu. Directions are mirrored when using Bootstrap in RTL, meaning `.dropdown-menu-end` will appear on the left side.
 
 {{< callout info >}}
-**Heads up!** Dropdowns are positioned thanks to Popper (except when they are contained in a navbar).
+**Heads up!** Dropdowns are positioned thanks to Popper except when they are contained in a navbar.
 {{< /callout >}}
 
 {{< example >}}
@@ -690,6 +692,89 @@ To align **left** the dropdown menu with the given breakpoint or larger, add `.d
 
 Note that you don't need to add a `data-bs-display="static"` attribute to dropdown buttons in navbars, since Popper isn't used in navbars.
 
+### Alignment options
+
+Taking most of the options shown above, here's a small kitchen sink demo of various dropdown alignment options in one place.
+
+{{< example >}}
+<div class="btn-group">
+  <button class="btn btn-secondary dropdown-toggle" type="button" id="dropdownMenuButton" data-bs-toggle="dropdown" aria-expanded="false">
+    Dropdown
+  </button>
+  <ul class="dropdown-menu" aria-labelledby="dropdownMenuButton">
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+  </ul>
+</div>
+
+<div class="btn-group">
+  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
+    Right-aligned menu
+  </button>
+  <ul class="dropdown-menu dropdown-menu-end">
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+  </ul>
+</div>
+
+<div class="btn-group">
+  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" data-bs-display="static" aria-expanded="false">
+    Left-aligned, right-aligned lg
+  </button>
+  <ul class="dropdown-menu dropdown-menu-lg-end">
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+  </ul>
+</div>
+
+<div class="btn-group">
+  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" data-bs-display="static" aria-expanded="false">
+    Right-aligned, left-aligned lg
+  </button>
+  <ul class="dropdown-menu dropdown-menu-end dropdown-menu-lg-start">
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+  </ul>
+</div>
+
+<div class="btn-group dropstart">
+  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
+    Dropstart
+  </button>
+  <ul class="dropdown-menu">
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+  </ul>
+</div>
+
+<div class="btn-group dropend">
+  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
+    Dropend
+  </button>
+  <ul class="dropdown-menu">
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+  </ul>
+</div>
+
+<div class="btn-group dropup">
+  <button type="button" class="btn btn-secondary dropdown-toggle" data-bs-toggle="dropdown" aria-expanded="false">
+    Dropup
+  </button>
+  <ul class="dropdown-menu">
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+    <li><a class="dropdown-item" href="#">Menu item</a></li>
+  </ul>
+</div>
+{{< /example >}}
+
 ## Menu content
 
 ### Headers

site/content/docs/5.0/migration.md

@@ -23,6 +23,7 @@ toc: true
 - Restored `offset` option for Dropdown, Popover and Tooltip plugins.
 - The default value for the `fallbackPlacements` is changed to `['top', 'right', 'bottom', 'left']` for better placement of popper elements.
 - All the events for the dropdown are now triggered on the dropdown toggle button and then bubbled up to the parent element.
+- Dropdown menus now have a `data-bs-popper="static"` attribute set when the positioning of the dropdown is static and `data-bs-popper="none"` when dropdown is in the navbar. This is added by our JavaScript and helps us use custom position styles without interfering with Popper's positioning.
 
 ## v5.0.0-beta1