dropdown.js

/**
 * --------------------------------------------------------------------------
 * Bootstrap (v5.0.0-beta1): dropdown.js
 * Licensed under MIT (https://github.com/twbs/bootstrap/blob/main/LICENSE)
 * --------------------------------------------------------------------------
 */

import * as Popper from '@popperjs/core'

import {
  defineJQueryPlugin,
  getElementFromSelector,
  isElement,
  isVisible,
  isRTL,
  noop,
  typeCheckConfig
} from './util/index'
import Data from './dom/data'
import EventHandler from './dom/event-handler'
import Manipulator from './dom/manipulator'
import SelectorEngine from './dom/selector-engine'
import BaseComponent from './base-component'

/**
 * ------------------------------------------------------------------------
 * Constants
 * ------------------------------------------------------------------------
 */

const NAME = 'dropdown'
const DATA_KEY = 'bs.dropdown'
const EVENT_KEY = `.${DATA_KEY}`
const DATA_API_KEY = '.data-api'

const ESCAPE_KEY = 'Escape'
const SPACE_KEY = 'Space'
const TAB_KEY = 'Tab'
const ARROW_UP_KEY = 'ArrowUp'
const ARROW_DOWN_KEY = 'ArrowDown'
const RIGHT_MOUSE_BUTTON = 2 // MouseEvent.button value for the secondary button, usually the right button

const REGEXP_KEYDOWN = new RegExp(`${ARROW_UP_KEY}|${ARROW_DOWN_KEY}|${ESCAPE_KEY}`)

const EVENT_HIDE = `hide${EVENT_KEY}`
const EVENT_HIDDEN = `hidden${EVENT_KEY}`
const EVENT_SHOW = `show${EVENT_KEY}`
const EVENT_SHOWN = `shown${EVENT_KEY}`
const EVENT_CLICK = `click${EVENT_KEY}`
const EVENT_CLICK_DATA_API = `click${EVENT_KEY}${DATA_API_KEY}`
const EVENT_KEYDOWN_DATA_API = `keydown${EVENT_KEY}${DATA_API_KEY}`
const EVENT_KEYUP_DATA_API = `keyup${EVENT_KEY}${DATA_API_KEY}`

const CLASS_NAME_DISABLED = 'disabled'
const CLASS_NAME_SHOW = 'show'
const CLASS_NAME_DROPUP = 'dropup'
const CLASS_NAME_DROPEND = 'dropend'
const CLASS_NAME_DROPSTART = 'dropstart'
const CLASS_NAME_NAVBAR = 'navbar'

const SELECTOR_DATA_TOGGLE = '[data-bs-toggle="dropdown"]'
const SELECTOR_FORM_CHILD = '.dropdown form'
const SELECTOR_MENU = '.dropdown-menu'
const SELECTOR_NAVBAR_NAV = '.navbar-nav'
const SELECTOR_VISIBLE_ITEMS = '.dropdown-menu .dropdown-item:not(.disabled):not(:disabled)'

const PLACEMENT_TOP = isRTL ? 'top-end' : 'top-start'
const PLACEMENT_TOPEND = isRTL ? 'top-start' : 'top-end'
const PLACEMENT_BOTTOM = isRTL ? 'bottom-end' : 'bottom-start'
const PLACEMENT_BOTTOMEND = isRTL ? 'bottom-start' : 'bottom-end'
const PLACEMENT_RIGHT = isRTL ? 'left-start' : 'right-start'
const PLACEMENT_LEFT = isRTL ? 'right-start' : 'left-start'

const Default = {
  offset: 0,
  flip: true,
  boundary: 'clippingParents',
  reference: 'toggle',
  display: 'dynamic',
  popperConfig: null
}

const DefaultType = {
  offset: '(number|string|function)',
  flip: 'boolean',
  boundary: '(string|element)',
  reference: '(string|element)',
  display: 'string',
  popperConfig: '(null|object)'
}

/**
 * ------------------------------------------------------------------------
 * Class Definition
 * ------------------------------------------------------------------------
 */

class Dropdown extends BaseComponent {
  constructor(element, config) {
    super(element)

    this._popper = null
    this._config = this._getConfig(config)
    this._menu = this._getMenuElement()
    this._inNavbar = this._detectNavbar()

    this._addEventListeners()
  }

  // Getters

  static get Default() {
    return Default
  }

  static get DefaultType() {
    return DefaultType
  }

  static get DATA_KEY() {
    return DATA_KEY
  }

  // Public

  toggle() {
    if (this._element.disabled || this._element.classList.contains(CLASS_NAME_DISABLED)) {
      return
    }

    const isActive = this._element.classList.contains(CLASS_NAME_SHOW)

    Dropdown.clearMenus()

    if (isActive) {
      return
    }

    this.show()
  }

  show() {
    if (this._element.disabled || this._element.classList.contains(CLASS_NAME_DISABLED) || this._menu.classList.contains(CLASS_NAME_SHOW)) {
      return
    }

    const parent = Dropdown.getParentFromElement(this._element)
    const relatedTarget = {
      relatedTarget: this._element
    }

    const showEvent = EventHandler.trigger(this._element, EVENT_SHOW, relatedTarget)

    if (showEvent.defaultPrevented) {
      return
    }

    // Totally disable Popper for Dropdowns in Navbar
    if (!this._inNavbar) {
      if (typeof Popper === 'undefined') {
        throw new TypeError('Bootstrap\'s dropdowns require Popper (https://popper.js.org)')
      }

      let referenceElement = this._element

      if (this._config.reference === 'parent') {
        referenceElement = parent
      } else if (isElement(this._config.reference)) {
        referenceElement = this._config.reference

        // Check if it's jQuery element
        if (typeof this._config.reference.jquery !== 'undefined') {
          referenceElement = this._config.reference[0]
        }
      }

      this._popper = Popper.createPopper(referenceElement, this._menu, this._getPopperConfig())
    }

    // If this is a touch-enabled device we add extra
    // empty mouseover listeners to the body's immediate children;
    // only needed because of broken event delegation on iOS
    // https://www.quirksmode.org/blog/archives/2014/02/mouse_event_bub.html
    if ('ontouchstart' in document.documentElement &&
      !parent.closest(SELECTOR_NAVBAR_NAV)) {
      [].concat(...document.body.children)
        .forEach(elem => EventHandler.on(elem, 'mouseover', null, noop()))
    }

    this._element.focus()
    this._element.setAttribute('aria-expanded', true)

    this._menu.classList.toggle(CLASS_NAME_SHOW)
    this._element.classList.toggle(CLASS_NAME_SHOW)
    EventHandler.trigger(parent, EVENT_SHOWN, relatedTarget)
  }

  hide() {
    if (this._element.disabled || this._element.classList.contains(CLASS_NAME_DISABLED) || !this._menu.classList.contains(CLASS_NAME_SHOW)) {
      return
    }

    const parent = Dropdown.getParentFromElement(this._element)
    const relatedTarget = {
      relatedTarget: this._element
    }

    const hideEvent = EventHandler.trigger(parent, EVENT_HIDE, relatedTarget)

    if (hideEvent.defaultPrevented) {
      return
    }

    if (this._popper) {
      this._popper.destroy()
    }

    this._menu.classList.toggle(CLASS_NAME_SHOW)
    this._element.classList.toggle(CLASS_NAME_SHOW)
    EventHandler.trigger(parent, EVENT_HIDDEN, relatedTarget)
  }

  dispose() {
    super.dispose()
    EventHandler.off(this._element, EVENT_KEY)
    this._menu = null

    if (this._popper) {
      this._popper.destroy()
      this._popper = null
    }
  }

  update() {
    this._inNavbar = this._detectNavbar()
    if (this._popper) {
      this._popper.update()
    }
  }

  // Private

  _addEventListeners() {
    EventHandler.on(this._element, EVENT_CLICK, event => {
      event.preventDefault()
      event.stopPropagation()
      this.toggle()
    })
  }

  _getConfig(config) {
    config = {
      ...this.constructor.Default,
      ...Manipulator.getDataAttributes(this._element),
      ...config
    }

    typeCheckConfig(NAME, config, this.constructor.DefaultType)

    return config
  }

  _getMenuElement() {
    return SelectorEngine.next(this._element, SELECTOR_MENU)[0]
  }

  _getPlacement() {
    const parentDropdown = this._element.parentNode

    if (parentDropdown.classList.contains(CLASS_NAME_DROPEND)) {
      return PLACEMENT_RIGHT
    }

    if (parentDropdown.classList.contains(CLASS_NAME_DROPSTART)) {
      return PLACEMENT_LEFT
    }

    // We need to trim the value because custom properties can also include spaces
    const isEnd = getComputedStyle(this._menu).getPropertyValue('--bs-position').trim() === 'end'

    if (parentDropdown.classList.contains(CLASS_NAME_DROPUP)) {
      return isEnd ? PLACEMENT_TOPEND : PLACEMENT_TOP
    }

    return isEnd ? PLACEMENT_BOTTOMEND : PLACEMENT_BOTTOM
  }

  _detectNavbar() {
    return this._element.closest(`.${CLASS_NAME_NAVBAR}`) !== null
  }

  _getPopperConfig() {
    const popperConfig = {
      placement: this._getPlacement(),
      modifiers: [{
        name: 'preventOverflow',
        options: {
          altBoundary: this._config.flip,
          rootBoundary: this._config.boundary
        }
      },
      {
        name: 'flip',
        options: {
          fallbackPlacements: ['top', 'right', 'bottom', 'left']
        }
      }]
    }

    // Disable Popper if we have a static display
    if (this._config.display === 'static') {
      popperConfig.modifiers = [{
        name: 'applyStyles',
        enabled: false
      }]
    }

    return {
      ...popperConfig,
      ...this._config.popperConfig
    }
  }

  // Static

  static dropdownInterface(element, config) {
    let data = Data.getData(element, DATA_KEY)
    const _config = typeof config === 'object' ? config : null

    if (!data) {
      data = new Dropdown(element, _config)
    }

    if (typeof config === 'string') {
      if (typeof data[config] === 'undefined') {
        throw new TypeError(`No method named "${config}"`)
      }

      data[config]()
    }
  }

  static jQueryInterface(config) {
    return this.each(function () {
      Dropdown.dropdownInterface(this, config)
    })
  }

  static clearMenus(event) {
    if (event && (event.button === RIGHT_MOUSE_BUTTON || (event.type === 'keyup' && event.key !== TAB_KEY))) {
      return
    }

    const toggles = SelectorEngine.find(SELECTOR_DATA_TOGGLE)

    for (let i = 0, len = toggles.length; i < len; i++) {
      const parent = Dropdown.getParentFromElement(toggles[i])
      const context = Data.getData(toggles[i], DATA_KEY)
      const relatedTarget = {
        relatedTarget: toggles[i]
      }

      if (event && event.type === 'click') {
        relatedTarget.clickEvent = event
      }

      if (!context) {
        continue
      }

      const dropdownMenu = context._menu
      if (!toggles[i].classList.contains(CLASS_NAME_SHOW)) {
        continue
      }

      if (event && ((event.type === 'click' &&
          /input|textarea/i.test(event.target.tagName)) ||
          (event.type === 'keyup' && event.key === TAB_KEY)) &&
          dropdownMenu.contains(event.target)) {
        continue
      }

      const hideEvent = EventHandler.trigger(parent, EVENT_HIDE, relatedTarget)
      if (hideEvent.defaultPrevented) {
        continue
      }

      // If this is a touch-enabled device we remove the extra
      // empty mouseover listeners we added for iOS support
      if ('ontouchstart' in document.documentElement) {
        [].concat(...document.body.children)
          .forEach(elem => EventHandler.off(elem, 'mouseover', null, noop()))
      }

      toggles[i].setAttribute('aria-expanded', 'false')

      if (context._popper) {
        context._popper.destroy()
      }

      dropdownMenu.classList.remove(CLASS_NAME_SHOW)
      toggles[i].classList.remove(CLASS_NAME_SHOW)
      EventHandler.trigger(parent, EVENT_HIDDEN, relatedTarget)
    }
  }

  static getParentFromElement(element) {
    return getElementFromSelector(element) || element.parentNode
  }

  static dataApiKeydownHandler(event) {
    // If not input/textarea:
    //  - And not a key in REGEXP_KEYDOWN => not a dropdown command
    // If input/textarea:
    //  - If space key => not a dropdown command
    //  - If key is other than escape
    //    - If key is not up or down => not a dropdown command
    //    - If trigger inside the menu => not a dropdown command
    if (/input|textarea/i.test(event.target.tagName) ?
      event.key === SPACE_KEY || (event.key !== ESCAPE_KEY &&
      ((event.key !== ARROW_DOWN_KEY && event.key !== ARROW_UP_KEY) ||
        event.target.closest(SELECTOR_MENU))) :
      !REGEXP_KEYDOWN.test(event.key)) {
      return
    }

    event.preventDefault()
    event.stopPropagation()

    if (this.disabled || this.classList.contains(CLASS_NAME_DISABLED)) {
      return
    }

    const parent = Dropdown.getParentFromElement(this)
    const isActive = this.classList.contains(CLASS_NAME_SHOW)

    if (event.key === ESCAPE_KEY) {
      const button = this.matches(SELECTOR_DATA_TOGGLE) ? this : SelectorEngine.prev(this, SELECTOR_DATA_TOGGLE)[0]
      button.focus()
      Dropdown.clearMenus()
      return
    }

    if (!isActive || event.key === SPACE_KEY) {
      Dropdown.clearMenus()
      return
    }

    const items = SelectorEngine.find(SELECTOR_VISIBLE_ITEMS, parent).filter(isVisible)

    if (!items.length) {
      return
    }

    let index = items.indexOf(event.target)

    // Up
    if (event.key === ARROW_UP_KEY && index > 0) {
      index--
    }

    // Down
    if (event.key === ARROW_DOWN_KEY && index < items.length - 1) {
      index++
    }

    // index is -1 if the first keydown is an ArrowUp
    index = index === -1 ? 0 : index

    items[index].focus()
  }
}

/**
 * ------------------------------------------------------------------------
 * Data Api implementation
 * ------------------------------------------------------------------------
 */

EventHandler.on(document, EVENT_KEYDOWN_DATA_API, SELECTOR_DATA_TOGGLE, Dropdown.dataApiKeydownHandler)
EventHandler.on(document, EVENT_KEYDOWN_DATA_API, SELECTOR_MENU, Dropdown.dataApiKeydownHandler)
EventHandler.on(document, EVENT_CLICK_DATA_API, Dropdown.clearMenus)
EventHandler.on(document, EVENT_KEYUP_DATA_API, Dropdown.clearMenus)
EventHandler.on(document, EVENT_CLICK_DATA_API, SELECTOR_DATA_TOGGLE, function (event) {
  event.preventDefault()
  event.stopPropagation()
  Dropdown.dropdownInterface(this, 'toggle')
})
EventHandler.on(document, EVENT_CLICK_DATA_API, SELECTOR_FORM_CHILD, e => e.stopPropagation())

/**
 * ------------------------------------------------------------------------
 * jQuery
 * ------------------------------------------------------------------------
 * add .Dropdown to jQuery only if jQuery is present
 */

defineJQueryPlugin(NAME, Dropdown)

export default Dropdown