react-menu-list

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.

The above example can be tried here:

https://streakyc.github.io/react-menu-list/example/

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

npm install
npm run example-build

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

npm run example-watch

Components

This project exports the following components:

MenuList

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", "down", "left", or "right". 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.

MenuItem

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 and prevCursorLocation optional property (see MenuList.moveCursor).
• 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.
• 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.

SubMenuItem

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'}.
• 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.

A SubMenuItem has the following public methods:

• open()
• close()
• toggle()

MenuListInspector

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): This calls moveCursor on the first descendant MenuList, or throws an error if none are found.

MenuButton

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.

A MenuButton supports the following props:

• menu, positionOptions, onWillOpen, onDidOpen, onWillClose: These work the same as the props on SubMenuItem.
• className, style: These are passed to the button element.

Dropdown

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! As of Flow v0.22, you must add the following entries to your .flowconfig file's options section for them to work:

[options]
esproposal.class_static_fields=enable
esproposal.class_instance_fields=enable

Changelog

1.1.0 (2016-04-01)

• Add a small delay before a submenu opens when the user hovers over a SubMenuItem. This makes SubMenuItem's behavior more consistent with OS X dropdown menus, and seems to make the submenu's appearance seem less jarring to the user.