/ Dropdown

React dropdown menu components

React dropdown menu components

react-menu-list

This project is a set of components for building menus with. This project works well for dropdown and autocomplete menus. The menus are correctly keyboard-accessible, and it includes polish like established desktop application menus have such as well-behaved submenus which stay open even if the user briefly moves the mouse over other menu items while moving toward the submenu's dropdown.

This project differs from other similar projects because it allows arbitrary elements to be in the menu, including allowing menu items to be nested into other elements, and allows custom menu items that take control of the cursor.

This project doesn't include much CSS styling for the menus. You need to bring your own CSS. This makes this project great for someone trying to match their application's existing style. It's recommended that your application create wrapper components around this project's components that add your application's CSS.

You can find its code in the example directory. The example may be compiled
by running:

yarn
yarn example-build

You can build the example with live editing enabled (using
react-transform-hmr and
browserify-hmr) by running:

yarn example-watch

Components

This project exports the following components:

This component defines a menu suitable for a dropdown. Whenever a MenuList is
rendered on the page, it will listen for keyboard button presses such as enter,
up, and down.

A MenuList supports the following props:

  • onItemChosen: This is an optional function which is called when an item in
    the menu is chosen by the user. The callback is passed a ChosenEvent object.
    This event object does not identify which item was chosen by the user. Use the
    MenuItem's onItemChosen prop instead if you want to know which item was
    picked.
  • onLeftPushed, onRightPushed: These are optional functions which are
    called when the user presses the left or right arrow key while the menu is
    open. The callback is passed a MenuEvent object.

A MenuList has the following public methods:

  • moveCursor(direction: Direction, prevCursorLocation: ?Rect): Move the
    cursor in the menu. direction must be the the string "up" or "down".
    prevCursorLocation may be an object with top, bottom, left, and
    right number properties, and it will be passed to the onHighlightChange
    callback of the newly selected MenuItem. (This property is only useful for
    when the cursor moves between two menu items which each implement their own
    cursor over their own subitems.)
  • hasHighlight(): Returns true if any items in the list are currently
    highlighted.

This component defines a selectable item in a MenuList. It should only be used
as a descendant of a MenuList. It does not need to be a direct child of the
MenuList component.

A MenuItem supports the following props:

  • onItemChosen: This is an optional function which is called when the item is
    chosen by the user. The callback is passed a ChosenEvent object.
  • onHighlightChange: This is an optional function which is called when the
    item is highlighted or unhighlighted by the user. The callback is passed a
    boolean representing whether the item is highlighted now, and if the item is
    highlighted, the second argument is an object with byKeyboard boolean
    property, prevCursorLocation optional property (see MenuList.moveCursor),
    and an optional direction string of "up" or "down" describing which key the
    user pressed to highlight the item.
  • onLeftPushed, onRightPushed: These are optional functions which are
    called when the user presses the left or right arrow key while the menu item
    is highlighted. The callback is passed a MenuEvent object.
  • className, style: These are optional and are passed as props to the
    MenuItem's underlying div.
  • highlightedClassName, highlightedStyle: These are optional and are
    combined with the className and style props and passed to the underlying div
    when the item is highlighted.
  • index: This an optional number which overrides the menu item's index in the
    MenuList for keyboard control purposes. The order of menu items is normally
    determined by their position in the DOM when mounted. This property should be
    unnecessary unless you're reordering mounted menu items. If any MenuItems
    within a MenuList use this prop, then all of them should.
  • onMouseLeave: This is an optional function which overrides the MenuItem's
    default onMouseLeave event handler, which is in charge of unhighlighting the
    menu item. Unless you're reimplementing SubMenuItem, you probably won't need
    this.

A MenuItem has the following public methods:

  • takeKeyboard(): This causes the parent MenuList to stop listening for
    keyboard events until releaseKeyboard() is called or this menu item is
    removed. Used by SubMenuItem when a dropdown menu is opened.
  • releaseKeyboard(): Cancels a previous takeKeyboard() call on this item.
  • lockHighlight(): This prevents other items in the MenuList from becoming
    highlighted by the mouse until unlockHighlight() is called or this menu item
    is removed. Used by SubMenuItem to provide a grace period before it becomes
    unhighlighted and closes its dropdown.
  • unlockHighlight(): Cancels a previous lockHighlight() call on this item.
  • highlight(byKeyboard: boolean=true): Attempt to highlight the menu item.
    If byKeyboard is false, then the attempt may not be successful if a highlight
    lock is in place.
  • unhighlight(): Attempt to unhighlight the menu item.
  • moveCursor(direction: Direction, prevCursorLocation: ?Rect): See
    menuList.moveCursor.
  • hasHighlight(): Returns true if the item is currently highlighted.

This component is similar to MenuItem, except that it defines a menu item that
displays a dropdown when selected. The dropdown can have a nested MenuList.
SubMenuItem automatically keeps the item selected and the dropdown open for a
short grace period when the user moves the mouse off of the menu item if
they're moving the mouse toward the dropdown.

A SubMenuItem supports the following props:

  • menu: This is the React element to show as the dropdown when the submenu is
    open.
  • positionOptions: This an optional object of options to control how the
    dropdown is aligned to the menu item. The options are the same as those
    supported by
    contain-by-screen (version ^1.0).
    This defaults to {position:'right', vAlign:'top', hAlign: 'left'}.
  • menuZIndex: This an optional number controlling the z-index CSS property of
    the menu's container.
  • onWillOpen: This is an optional function called before the submenu opens.
  • onDidOpen: This is an optional function called after the submenu opened.
  • onWillClose: This is an optional function called before the submenu closes.
  • className, style, highlightedClassName, highlightedStyle, index,
    onItemChosen, onHighlightChange: These props are all passed through to the
    underlying MenuItem element.
  • openedClassName, openedStyle: These are optional and are combined with
    the className and style props and passed to the underlying div when the item
    is opened.

A SubMenuItem has the following public methods:

  • open(callback?: Function)
  • close()
  • toggle()
  • reposition(): Repositions the floating submenu. Call this if you change the
    size of the menu.
  • highlight(byKeyboard: boolean=true): Attempt to highlight the menu item.
    If byKeyboard is false, then the attempt may not be successful if a highlight
    lock is in place. If byKeyboard is false, then the highlight will trigger the
    submenu to display.
  • unhighlight(): Attempt to unhighlight the menu item.
  • moveCursor(direction: Direction, prevCursorLocation: ?Rect): See
    menuList.moveCursor.
  • hasHighlight(): Returns true if the item is currently highlighted.

This component lets you manipulate and listen to events from descendant
MenuList elements. See the Events section for more information. This component
is used by MenuButton to detect when a MenuList provided to it has been clicked
on, and by SubMenuItem to trigger highlighting its submenu.

A MenuListInspector supports the following props:

  • onItemChosen, onLeftPushed, onRightPushed: These work the same as on
    MenuList.

A MenuListInspector has the following public methods:

  • moveCursor(direction: Direction, prevCursorLocation: ?Rect): boolean: This
    calls moveCursor on the first descendant MenuList and returns true, or returns
    false if no descendant MenuLists were found.
  • hasHighlight(): Returns true if any descendant lists currently have a
    highlighted item.

This is a button which shows a dropdown when pressed. You can put a MenuList
into the dropdown, and the MenuButton will close the dropdown once a menu item
is chosen. You can avoid having the MenuButton close when an item is chosen by
calling the stopPropagation method on the ChosenEvent object passed to the
MenuItem's onItemChosen callback.

A MenuButton supports the following props:

  • menu, positionOptions, menuZIndex, onWillOpen, onDidOpen,
    onWillClose, className, style, openedClassName, openedStyle:
    These work the same as the props on SubMenuItem.
  • disabled, title: These are passed to the button element.
  • ButtonComponent: Optional prop that allows a different component to be used
    instead of an html <button>.

A MenuButton has the following public methods:

  • open(callback?: Function)
  • close()
  • toggle()
  • reposition(): Repositions the floating submenu. Call this if you change the
    size of the menu.

This is just a div with a bit of CSS on it to form the container for dropdown
contents. It's provided for convenience for use with SubMenuItem and
MenuButton. This component doesn't have any logic, so feel free to substitute
it with a component with styling more specific to your application.

This component supports no props besides children, which is passed through to
the underlying div.

Events

Many callback props are called with a MenuEvent object. MenuEvents bubble
between components. A MenuEvent is first emitted on the originating MenuItem,
then the parent MenuList, and then on each MenuListInspector going upwards.

A MenuEvent object has a type string property, and preventDefault and
stopPropagation methods. Calling the preventDefault or stopPropagation
methods will cause the same method to be triggered on the source DOM event
object. Additionally, then stopPropagation method will stop the MenuEvent
from bubbling up to the parent menu components.

Some callback props are passed a ChosenEvent object, which extends the
MenuEvent class with a byKeyboard boolean property.

Types

Flow type declarations for this module are included!
If you are using Flow, they won't require any configuration to use.

GitHub