Via data attributes or JavaScript, the dropdown plugin toggles hidden content (dropdown menus) by toggling the `.show` class on the parent list item.
-On mobile devices, opening a dropdown adds a `.dropdown-backdrop` as a tap area for closing dropdown menus when tapping outside the menu, a requirement for proper iOS support. **This means that switching from an open dropdown menu to a different dropdown menu requires an extra tap on mobile.**
+On touch-enabled devices, opening a dropdown adds a `.dropdown-backdrop` as a tap area for closing dropdown menus when tapping outside the menu, to work around a quirk in iOS' event delegation. **This means that once a dropdown menu is open, any tap or click (including with a mouse, on a multi-input device such as a laptop with a touchscreen) outside of the menu will be intercepted to close the menu. Opening another dropdown menu, or activating any other control or link, will therefore require an extra tap or click.**
Note: The `data-toggle="dropdown"` attribute is relied on for closing dropdown menus at an application level, so it's a good idea to always use it.
if ('ontouchstart' in document.documentElement &&
!$(parent).closest(Selector.NAVBAR_NAV).length) {
- // if mobile we use a backdrop because click events don't delegate
- const dropdown = document.createElement('div')
- dropdown.className = ClassName.BACKDROP
- $(dropdown).insertBefore(this)
- $(dropdown).on('click', Dropdown._clearMenus)
+ // if touch-enabled device we use a backdrop because click events
+ // don't delegate on iOS - see https://www.quirksmode.org/blog/archives/2014/02/mouse_event_bub.html
+ const backdrop = document.createElement('div')
+ backdrop.className = ClassName.BACKDROP
+ $(backdrop).insertBefore(this)
+ $(backdrop).on('click', Dropdown._clearMenus)
}
this.focus()