Add modal dialogue component

src/govuk/all.js

@@ -6,6 +6,7 @@ import CharacterCount from './components/character-count/character-count'
 import Checkboxes from './components/checkboxes/checkboxes'
 import ErrorSummary from './components/error-summary/error-summary'
 import Header from './components/header/header'
+import ModalDialogue from './components/modal-dialogue/modal-dialogue'
 import Radios from './components/radios/radios'
 import Tabs from './components/tabs/tabs'
 
@@ -50,6 +51,11 @@ function initAll (options) {
   var $toggleButton = scope.querySelector('[data-module="govuk-header"]')
   new Header($toggleButton).init()
 
+  var $modals = scope.querySelectorAll('[data-module="govuk-modal-dialogue"]')
+  nodeListForEach($modals, function ($modal) {
+    new ModalDialogue($modal).init()
+  })
+
   var $radios = scope.querySelectorAll('[data-module="govuk-radios"]')
   nodeListForEach($radios, function ($radio) {
     new Radios($radio).init()

src/govuk/components/_all.scss

@@ -17,6 +17,7 @@
 @import "input/input";
 @import "inset-text/inset-text";
 @import "label/label";
+@import "modal-dialogue/modal-dialogue";
 @import "panel/panel";
 @import "phase-banner/phase-banner";
 @import "tabs/tabs";

src/govuk/components/modal-dialogue/_modal-dialogue.scss

@@ -0,0 +1,164 @@
+// Disables linting for this file only
+// sass-lint:disable no-duplicate-properties
+
+@import "../../settings/all";
+@import "../../tools/all";
+@import "../../helpers/all";
+
+@include govuk-exports("govuk/component/modal-dialogue") {
+  $govuk-dialogue-width: 640px;
+
+  .govuk-modal-dialogue,
+  .govuk-modal-dialogue__backdrop {
+    position: fixed;
+    z-index: 0;
+    top: 0;
+    left: 0;
+    width: 100%;
+    height: 100%;
+  }
+
+  // Hide dialogue when closed
+  .govuk-modal-dialogue {
+    display: none;
+  }
+
+  // Show dialogue when opened
+  .govuk-modal-dialogue--open {
+    display: block;
+  }
+
+  // Wrapper to handle overflow scrolling
+  .govuk-modal-dialogue__wrapper {
+    box-sizing: border-box;
+    display: flex;
+    height: 100%;
+    @include govuk-responsive-padding(7, "top");
+    @include govuk-responsive-padding(7, "bottom");
+    overflow-y: auto;
+    align-items: flex-start;
+    align-items: safe center;
+  }
+
+  // HTML5 dialogue component
+  .govuk-modal-dialogue__box {
+    box-sizing: border-box;
+    display: block;
+    position: relative;
+    z-index: 1;
+    width: 90%;
+    margin: auto;
+    padding: 0;
+    overflow-y: auto;
+    border: $govuk-focus-width solid govuk-colour("black");
+    background: govuk-colour("white");
+
+    // Add focus outline to dialogue
+    &:focus {
+      outline: $govuk-focus-width solid $govuk-focus-colour;
+    }
+
+    // Hide browser backdrop
+    &::backdrop {
+      display: none;
+    }
+  }
+
+  // Header with close button
+  .govuk-modal-dialogue__header {
+    @include govuk-clearfix;
+    @include govuk-responsive-margin(5, "bottom");
+    padding-bottom: $govuk-focus-width;
+    color: govuk-colour("white");
+    background-color: govuk-colour("black");
+    text-align: right;
+  }
+
+  // Inner content
+  .govuk-modal-dialogue__content {
+    @include govuk-font($size: 16);
+    @include govuk-responsive-padding(6);
+    padding-top: 0;
+  }
+
+  .govuk-modal-dialogue__description {
+    @include govuk-responsive-margin(4, "bottom");
+  }
+
+  // Remove bottom margins
+  .govuk-modal-dialogue__description:last-child,
+  .govuk-modal-dialogue__description > :last-child,
+  .govuk-modal-dialogue__content > :last-child {
+    margin-bottom: 0;
+  }
+
+  // Custom backdrop
+  .govuk-modal-dialogue__backdrop {
+    opacity: .8;
+    background: govuk-colour("black");
+    pointer-events: none;
+    touch-action: none;
+  }
+
+  // Crown icon
+  .govuk-modal-dialogue__crown {
+    display: block;
+    margin: 6px 0 0 6px;
+    @include govuk-responsive-margin(5, "left");
+    float: left;
+  }
+
+  // Heading
+  .govuk-modal-dialogue__heading:last-child {
+    margin-bottom: 0;
+  }
+
+  // Close button
+  .govuk-modal-dialogue__close {
+    $font-size: 36px;
+    $line-height: 1;
+
+    display: block;
+    width: auto;
+    min-width: 44px;
+    margin: 0;
+    padding: 2px 5px;
+    float: right;
+    color: govuk-colour("white");
+    background-color: govuk-colour("black");
+    box-shadow: none !important;
+    font-size: $font-size;
+    @if $govuk-typography-use-rem {
+      font-size: govuk-px-to-rem($font-size);
+    }
+    @include govuk-typography-weight-bold;
+    line-height: $line-height;
+
+    &:hover {
+      color: govuk-colour("black");
+      background-color: govuk-colour("yellow");
+    }
+
+    &:active {
+      top: 0;
+    }
+  }
+
+  // New dialogue width, inline button + link
+  @include govuk-media-query($from: tablet) {
+    .govuk-modal-dialogue__content {
+      padding-top: 0;
+    }
+
+    .govuk-modal-dialogue__box {
+      width: percentage($govuk-dialogue-width / map-get($govuk-breakpoints, desktop));
+    }
+  }
+
+  // Fixed width
+  @include govuk-media-query($from: desktop) {
+    .govuk-modal-dialogue__box {
+      width: $govuk-dialogue-width;
+    }
+  }
+}

src/govuk/components/modal-dialogue/macro.njk

@@ -0,0 +1,3 @@
+{% macro govukModalDialogue(params) %}
+  {%- include "./template.njk" -%}
+{% endmacro %}

src/govuk/components/modal-dialogue/modal-dialogue.js

@@ -0,0 +1,186 @@
+import { nodeListForEach } from '../../common'
+import '../../vendor/polyfills/Element/prototype/classList'
+import '../../vendor/polyfills/Function/prototype/bind'
+import '../../vendor/polyfills/Event' // addEventListener and event.target normaliziation
+
+function ModalDialogue ($module) {
+  this.$module = $module
+  this.$dialogBox = $module.querySelector('dialog')
+  this.$container = document.documentElement
+
+  // Check for browser support
+  this.hasNativeDialog = 'showModal' in this.$dialogBox
+
+  // Allowed focussable elements
+  this.focussable = [
+    'button',
+    '[href]',
+    'input',
+    'select',
+    'textarea'
+  ]
+}
+
+// Initialize component
+ModalDialogue.prototype.init = function (options) {
+  this.options = options || {}
+
+  this.open = this.handleOpen.bind(this)
+  this.close = this.handleClose.bind(this)
+  this.focus = this.handleFocus.bind(this)
+  this.focusTrap = this.handleFocusTrap.bind(this)
+  this.boundKeyDown = this.handleKeyDown.bind(this)
+
+  // Modal elements
+  this.$buttonClose = this.$dialogBox.querySelector('.govuk-modal-dialogue__close')
+  this.$focussable = this.$dialogBox.querySelectorAll(this.focussable.toString())
+  this.$focusableLast = this.$focussable[this.$focussable.length - 1]
+  this.$focusElement = this.options.focusElement || this.$dialogBox
+
+  if (this.$dialogBox.hasAttribute('open')) {
+    this.open()
+  }
+
+  this.initEvents()
+
+  return this
+}
+
+// Initialize component events
+ModalDialogue.prototype.initEvents = function (options) {
+  if (this.options.triggerElement) {
+    this.options.triggerElement.addEventListener('click', this.open)
+  }
+
+  // Close dialogue on close button click
+  this.$buttonClose.addEventListener('click', this.close)
+}
+
+// Open modal
+ModalDialogue.prototype.handleOpen = function (event) {
+  if (event) {
+    event.preventDefault()
+  }
+
+  // Save last-focussed element
+  this.$lastActiveElement = document.activeElement
+
+  // Disable scrolling, show wrapper
+  this.$container.classList.add('govuk-!-scroll-disabled')
+  this.$module.classList.add('govuk-modal-dialogue--open')
+
+  // Close on escape key, trap focus
+  document.addEventListener('keydown', this.boundKeyDown, true)
+
+  // Optional 'onOpen' callback
+  if (typeof this.options.onOpen === 'function') {
+    this.options.onOpen.call(this)
+  }
+
+  // Skip open if already open
+  if (this.$dialogBox.hasAttribute('open')) {
+    return
+  }
+
+  // Show modal
+  this.hasNativeDialog
+    ? this.$dialogBox.show()
+    : this.$dialogBox.setAttribute('open', '')
+
+  // Handle focus
+  this.focus()
+}
+
+// Close modal
+ModalDialogue.prototype.handleClose = function (event) {
+  if (event) {
+    event.preventDefault()
+  }
+
+  // Skip close if already closed
+  if (!this.$dialogBox.hasAttribute('open')) {
+    return
+  }
+
+  // Hide modal
+  this.hasNativeDialog
+    ? this.$dialogBox.close()
+    : this.$dialogBox.removeAttribute('open')
+
+  // Hide wrapper, enable scrolling
+  this.$module.classList.remove('govuk-modal-dialogue--open')
+  this.$container.classList.remove('govuk-!-scroll-disabled')
+
+  // Restore focus to last active element
+  this.$lastActiveElement.focus()
+
+  // Optional 'onClose' callback
+  if (typeof this.options.onClose === 'function') {
+    this.options.onClose.call(this)
+  }
+
+  // Remove escape key and trap focus listener
+  document.removeEventListener('keydown', this.boundKeyDown, true)
+}
+
+// Lock scroll, focus modal
+ModalDialogue.prototype.handleFocus = function () {
+  this.$dialogBox.scrollIntoView()
+  this.$focusElement.focus({ preventScroll: true })
+}
+
+// Ensure focus stays within modal
+ModalDialogue.prototype.handleFocusTrap = function (event) {
+  var $focusElement
+
+  // Check for tabbing outside dialog
+  var hasFocusEscaped = document.activeElement !== this.$dialogBox
+
+  // Loop inner focussable elements
+  if (hasFocusEscaped) {
+    nodeListForEach(this.$focussable, function (element) {
+      // Actually, focus is on an inner focussable element
+      if (hasFocusEscaped && document.activeElement === element) {
+        hasFocusEscaped = false
+      }
+    })
+
+    // Wrap focus back to first element
+    $focusElement = hasFocusEscaped
+      ? this.$dialogBox
+      : undefined
+  }
+
+  // Wrap focus back to first/last element
+  if (!$focusElement) {
+    if ((document.activeElement === this.$focusableLast && !event.shiftKey) || !this.$focussable.length) {
+      $focusElement = this.$dialogBox
+    } else if (document.activeElement === this.$dialogBox && event.shiftKey) {
+      $focusElement = this.$focusableLast
+    }
+  }
+
+  // Wrap focus
+  if ($focusElement) {
+    event.preventDefault()
+    $focusElement.focus({ preventScroll: true })
+  }
+}
+
+// Listen for key presses
+ModalDialogue.prototype.handleKeyDown = function (event) {
+  var KEY_TAB = 9
+  var KEY_ESCAPE = 27
+
+  switch (event.keyCode) {
+    case KEY_TAB:
+      this.focusTrap(event)
+      break
+
+    case KEY_ESCAPE:
+      this.close()
+      break
+  }
+}
+
+export default ModalDialogue