element3/src/utils/aria-dialog.js

A Component Library for Vue3

/* eslint-disable no-use-before-define */
import Utils from './aria-utils'

/**
 * @constructor
 * @desc Dialog object providing modal focus management.
 *
 * Assumptions: The element serving as the dialog container is present in the
 * DOM and hidden. The dialog container has role='dialog'.
 *
 * @param dialogId
 *          The ID of the element serving as the dialog container.
 * @param focusAfterClosed
 *          Either the DOM node or the ID of the DOM node to focus when the
 *          dialog closes.
 * @param focusFirst
 *          Optional parameter containing either the DOM node or the ID of the
 *          DOM node to focus when the dialog opens. If not specified, the
 *          first focusable element in the dialog will receive focus.
 */
var aria = aria || {}
var tabEvent

aria.Dialog = function (dialog, focusAfterClosed, focusFirst) {
  this.dialogNode = dialog
  if (
    this.dialogNode === null ||
    this.dialogNode.getAttribute('role') !== 'dialog'
  ) {
    throw new Error('Dialog() requires a DOM element with ARIA role of dialog.')
  }

  if (typeof focusAfterClosed === 'string') {
    this.focusAfterClosed = document.getElementById(focusAfterClosed)
  } else if (typeof focusAfterClosed === 'object') {
    this.focusAfterClosed = focusAfterClosed
  } else {
    this.focusAfterClosed = null
  }

  if (typeof focusFirst === 'string') {
    this.focusFirst = document.getElementById(focusFirst)
  } else if (typeof focusFirst === 'object') {
    this.focusFirst = focusFirst
  } else {
    this.focusFirst = null
  }

  if (this.focusFirst) {
    this.focusFirst.focus()
  } else {
    Utils.focusFirstDescendant(this.dialogNode)
  }

  this.lastFocus = document.activeElement
  tabEvent = (e) => {
    this.trapFocus(e)
  }
  this.addListeners()
}

aria.Dialog.prototype.addListeners = function () {
  document.addEventListener('focus', tabEvent, true)
}

aria.Dialog.prototype.removeListeners = function () {
  document.removeEventListener('focus', tabEvent, true)
}

aria.Dialog.prototype.closeDialog = function () {
  this.removeListeners()
  if (this.focusAfterClosed) {
    setTimeout(() => {
      this.focusAfterClosed.focus()
    })
  }
}

aria.Dialog.prototype.trapFocus = function (event) {
  if (Utils.IgnoreUtilFocusChanges) {
    return
  }
  if (this.dialogNode.contains(event.target)) {
    this.lastFocus = event.target
  } else {
    Utils.focusFirstDescendant(this.dialogNode)
    if (this.lastFocus === document.activeElement) {
      Utils.focusLastDescendant(this.dialogNode)
    }
    this.lastFocus = document.activeElement
  }
}

export default aria.Dialog