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Merge pull request #30 from github/feat-add-focus-management-for-toolbar
Feat add focus management for toolbar
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‎README.md

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@@ -28,10 +28,13 @@ import '@github/markdown-toolbar-element'
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<md-task-list>task-list</md-task-list>
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<md-mention>mention</md-mention>
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<md-ref>ref</md-ref>
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<button data-md-button>Custom button</button>
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</markdown-toolbar>
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<textarea id="textarea_id"></textarea>
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```
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`<markdown-toolbar>` comes with focus management as advised in [WAI-ARIA Authoring Practices 1.1: Toolbar Design Pattern](https://www.w3.org/TR/wai-aria-practices-1.1/examples/toolbar/toolbar.html). The `md-*` buttons that ship with this package are automatically managed. Add a `data-md-button` attribute to any custom toolbar items to enroll them into focus management.
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## Browser support
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Browsers without native [custom element support][support] require a [polyfill][].

‎examples/index.html

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@@ -6,6 +6,7 @@
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</head>
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<body>
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<div class="container py-4">
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<p><button type="button">Add a Comment</button></p>
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<markdown-toolbar for="textarea">
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<md-bold class="btn btn-sm">bold</md-bold>
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<md-header class="btn btn-sm">header</md-header>
@@ -22,6 +23,29 @@
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</markdown-toolbar>
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<textarea rows="6" class="mt-3 d-block width-full" id="textarea"></textarea>
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</div>
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<details class="container py-4">
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<summary>Initially hidden toolbar!</summary>
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<div class="container py-4">
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<p><button type="button">Add a Comment</button></p>
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<markdown-toolbar for="textarea2">
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<md-bold class="btn btn-sm">bold</md-bold>
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<md-header class="btn btn-sm">header</md-header>
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<md-italic class="btn btn-sm">italic</md-italic>
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<md-quote class="btn btn-sm">quote</md-quote>
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<md-code class="btn btn-sm">code</md-code>
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<md-link class="btn btn-sm">link</md-link>
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<md-image class="btn btn-sm">image</md-image>
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<md-unordered-list class="btn btn-sm">unordered-list</md-unordered-list>
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<md-ordered-list class="btn btn-sm">ordered-list</md-ordered-list>
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<md-task-list class="btn btn-sm">task-list</md-task-list>
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<md-mention class="btn btn-sm">mention</md-mention>
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<md-ref class="btn btn-sm">ref</md-ref>
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</markdown-toolbar>
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<textarea rows="6" class="mt-3 d-block width-full" id="textarea2"></textarea>
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</div>
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</details>
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<script>
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const script = document.createElement('script')
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if (window.location.hostname.endsWith('github.io') || window.location.hostname.endsWith('github.com')) {

‎index.js

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@@ -1,5 +1,30 @@
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/* @flow strict */
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const buttonSelectors = [
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'[data-md-button]',
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'md-header',
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'md-bold',
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'md-italic',
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'md-quote',
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'md-code',
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'md-link',
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'md-image',
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'md-unordered-list',
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'md-ordered-list',
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'md-task-list',
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'md-mention',
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'md-ref'
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]
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function getButtons(toolbar: Element): HTMLElement[] {
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const els = []
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for (const button of toolbar.querySelectorAll(buttonSelectors.join(', '))) {
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// Skip buttons that are hidden, either via `hidden` attribute or CSS:
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if (button.hidden || (button.offsetWidth <= 0 && button.offsetHeight <= 0)) continue
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if (button.closest('markdown-toolbar') === toolbar) els.push(button)
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}
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return els
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}
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function keydown(fn: KeyboardEventHandler): KeyboardEventHandler {
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return function(event: KeyboardEvent) {
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if (event.key === ' ' || event.key === 'Enter') {
@@ -24,10 +49,6 @@ class MarkdownButtonElement extends HTMLElement {
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}
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connectedCallback() {
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if (!this.hasAttribute('tabindex')) {
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this.setAttribute('tabindex', '0')
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}
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if (!this.hasAttribute('role')) {
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this.setAttribute('role', 'button')
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}
@@ -221,11 +242,17 @@ class MarkdownToolbarElement extends HTMLElement {
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}
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connectedCallback() {
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if (!this.hasAttribute('role')) {
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this.setAttribute('role', 'toolbar')
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}
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this.addEventListener('keydown', focusKeydown)
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const fn = shortcut.bind(null, this)
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if (this.field) {
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this.field.addEventListener('keydown', fn)
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shortcutListeners.set(this, fn)
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}
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this.setAttribute('tabindex', '0')
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this.addEventListener('focus', onToolbarFocus, {once: true})
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}
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disconnectedCallback() {
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this.field.removeEventListener('keydown', fn)
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shortcutListeners.delete(this)
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}
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this.removeEventListener('keydown', focusKeydown)
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}
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get field(): ?HTMLTextAreaElement {
@@ -244,6 +272,46 @@ class MarkdownToolbarElement extends HTMLElement {
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}
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}
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function onToolbarFocus({target}: FocusEvent) {
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if (!(target instanceof Element)) return
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target.removeAttribute('tabindex')
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let tabindex = '0'
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for (const button of getButtons(target)) {
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button.setAttribute('tabindex', tabindex)
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if (tabindex === '0') {
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button.focus()
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tabindex = '-1'
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}
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}
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}
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function focusKeydown(event: KeyboardEvent) {
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const key = event.key
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if (key !== 'ArrowRight' && key !== 'ArrowLeft' && key !== 'Home' && key !== 'End') return
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const toolbar = event.currentTarget
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if (!(toolbar instanceof HTMLElement)) return
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const buttons = getButtons(toolbar)
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const index = buttons.indexOf(event.target)
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const length = buttons.length
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if (index === -1) return
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let n = 0
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if (key === 'ArrowLeft') n = index - 1
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if (key === 'ArrowRight') n = index + 1
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if (key === 'End') n = length - 1
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if (n < 0) n = length - 1
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if (n > length - 1) n = 0
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for (let i = 0; i < length; i += 1) {
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buttons[i].setAttribute('tabindex', i === n ? '0' : '-1')
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}
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// Need to stop home/end scrolling:
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event.preventDefault()
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buttons[n].focus()
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}
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const shortcutListeners = new WeakMap()
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function shortcut(toolbar: Element, event: KeyboardEvent) {

‎test/test.js

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@@ -71,7 +71,11 @@ describe('markdown-toolbar-element', function() {
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<md-bold>bold</md-bold>
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<md-header>header</md-header>
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<md-header level="1">h1</md-header>
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<div hidden>
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<md-header level="5">h5</md-header>
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</div>
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<md-header level="10">h1</md-header>
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<div data-md-button>Other button</div>
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<md-italic>italic</md-italic>
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<md-quote>quote</md-quote>
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<md-code>code</md-code>
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document.body.innerHTML = ''
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})
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describe('focus management', function() {
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function focusFirstButton() {
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const button = document.querySelector('md-bold')
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button.focus()
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}
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function pushKeyOnFocussedButton(key) {
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const event = document.createEvent('Event')
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event.initEvent('keydown', true, true)
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event.key = key
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document.activeElement.dispatchEvent(event)
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}
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function getElementsWithTabindex(index) {
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return [...document.querySelectorAll(`markdown-toolbar [tabindex="${index}"]`)]
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}
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beforeEach(() => {
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document.querySelector('markdown-toolbar').focus()
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})
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it('moves focus to next button when ArrowRight is pressed', function() {
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focusFirstButton()
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pushKeyOnFocussedButton('ArrowRight')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-header')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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pushKeyOnFocussedButton('ArrowRight')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-header[level="1"]')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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pushKeyOnFocussedButton('ArrowRight')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-header[level="10"]')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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})
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it('cycles focus round to last element from first when ArrowLeft is pressed', function() {
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focusFirstButton()
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pushKeyOnFocussedButton('ArrowLeft')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-ref')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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pushKeyOnFocussedButton('ArrowLeft')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-mention')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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})
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it('focussed first/last button when Home/End key is pressed', function() {
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focusFirstButton()
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pushKeyOnFocussedButton('End')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-ref')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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pushKeyOnFocussedButton('End')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-ref')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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pushKeyOnFocussedButton('Home')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-bold')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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pushKeyOnFocussedButton('Home')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('md-bold')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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})
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it('counts `data-md-button` elements in the focussable set', function() {
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focusFirstButton()
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pushKeyOnFocussedButton('ArrowRight')
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pushKeyOnFocussedButton('ArrowRight')
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pushKeyOnFocussedButton('ArrowRight')
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pushKeyOnFocussedButton('ArrowRight')
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assert.equal(getElementsWithTabindex(-1).length, 14)
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assert.deepEqual(getElementsWithTabindex(0), [document.querySelector('div[data-md-button]')])
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assert.deepEqual(getElementsWithTabindex(0), [document.activeElement])
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})
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})
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describe('bold', function() {
96181
it('bold selected text when you click the bold icon', function() {
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setVisualValue('The |quick| brown fox jumps over the lazy dog')

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