Add setting for selecting first option by default

README.md

@@ -15,11 +15,12 @@ $ npm install @github/combobox-nav
 ```html
 <label>
   Robot
-  <input id="robot-input" type="text">
+  <input id="robot-input" type="text" />
 </label>
 <ul role="listbox" id="list-id" hidden>
   <li id="baymax" role="option">Baymax</li>
-  <li><del>BB-8</del></li><!-- `role=option` needs to be present for item to be selectable -->
+  <li><del>BB-8</del></li>
+  <!-- `role=option` needs to be present for item to be selectable -->
   <li id="hubot" role="option">Hubot</li>
   <li id="r2-d2" role="option">R2-D2</li>
 </ul>
@@ -59,27 +60,29 @@ A bubbling `combobox-commit` event is fired on the list element when an option i
 For example, autocomplete when an option is selected:
 
 ```js
-list.addEventListener('combobox-commit', function(event) {
+list.addEventListener('combobox-commit', function (event) {
   console.log('Element selected: ', event.target)
 })
 ```
 
-**⚠ Note:** When using `<label>` + `<input>` as options, please listen on `change` instead of `combobox-commit`.
+> **Note** When using `<label>` + `<input>` as options, please listen on `change` instead of `combobox-commit`.
 
 When a label is clicked on, `click` event is fired from both `<label>` and its associated input `label.control`. Since combobox does not know about the control, `combobox-commit` cannot be used as an indicator of the item's selection state.
 
 ## Settings
 
-For advanced configuration, the constructor takes an optional third argument. This is a settings object with the following setting:
-
-- `tabInsertsSuggestions: boolean = true` -  Control whether the highlighted suggestion is inserted when <kbd>Tab</kbd> is pressed (<kbd>Enter</kbd> will always insert a suggestion regardless of this setting). When `true`, tab-navigation will be hijacked when open (which can have negative impacts on accessibility) but the combobox will more closely imitate a native IDE experience.
-
-For example:
+For advanced configuration, the constructor takes an optional third argument. For example:
 
 ```js
 const combobox = new Combobox(input, list, {tabInsertsSuggestions: true})
 ```
 
+These settings are available:
+
+- `tabInsertsSuggestions: boolean = true` - Control whether the highlighted suggestion is inserted when <kbd>Tab</kbd> is pressed (<kbd>Enter</kbd> will always insert a suggestion regardless of this setting). When `true`, tab-navigation will be hijacked when open (which can have negative impacts on accessibility) but the combobox will more closely imitate a native IDE experience.
+- `defaultFirstOption: boolean = false` - If no options are selected and the user presses <kbd>Enter</kbd>, should the first item be inserted? If enabled, the default option can be selected and styled with `[data-combobox-option-default]` . This should be styled differently from the `aria-selected` option.
+  > **Warning** Screen readers will not announce that the first item is the default. This should be announced explicitly with the use of `aria-live` status text.
+
 ## Development
 
 ```

src/index.ts

@@ -1,5 +1,6 @@
 export type ComboboxSettings = {
   tabInsertsSuggestions?: boolean
+  defaultFirstOption?: boolean
 }
 
 export default class Combobox {
@@ -11,15 +12,17 @@ export default class Combobox {
   inputHandler: (event: Event) => void
   ctrlBindings: boolean
   tabInsertsSuggestions: boolean
+  defaultFirstOption: boolean
 
   constructor(
     input: HTMLTextAreaElement | HTMLInputElement,
     list: HTMLElement,
-    {tabInsertsSuggestions}: ComboboxSettings = {}
+    {tabInsertsSuggestions, defaultFirstOption}: ComboboxSettings = {}
   ) {
     this.input = input
     this.list = list
     this.tabInsertsSuggestions = tabInsertsSuggestions ?? true
+    this.defaultFirstOption = defaultFirstOption ?? false
 
     this.isComposing = false
 
@@ -57,6 +60,7 @@ export default class Combobox {
     this.input.addEventListener('input', this.inputHandler)
     ;(this.input as HTMLElement).addEventListener('keydown', this.keyboardEventHandler)
     this.list.addEventListener('click', commitWithElement)
+    this.indicateDefaultOption()
   }
 
   stop(): void {
@@ -69,6 +73,14 @@ export default class Combobox {
     this.list.removeEventListener('click', commitWithElement)
   }
 
+  indicateDefaultOption(): void {
+    if (this.defaultFirstOption) {
+      Array.from(this.list.querySelectorAll<HTMLElement>('[role="option"]:not([aria-disabled="true"])'))
+        .filter(visible)[0]
+        .setAttribute('data-combobox-option-default', 'true')
+    }
+  }
+
   navigate(indexDiff: -1 | 1 = 1): void {
     const focusEl = Array.from(this.list.querySelectorAll<HTMLElement>('[aria-selected="true"]')).filter(visible)[0]
     const els = Array.from(this.list.querySelectorAll<HTMLElement>('[role="option"]')).filter(visible)
@@ -88,22 +100,26 @@ export default class Combobox {
 
     const target = els[indexOfItem]
     if (!target) return
+
     for (const el of els) {
+      el.removeAttribute('data-combobox-option-default')
+
       if (target === el) {
         this.input.setAttribute('aria-activedescendant', target.id)
         target.setAttribute('aria-selected', 'true')
         scrollTo(this.list, target)
       } else {
-        el.setAttribute('aria-selected', 'false')
+        el.removeAttribute('aria-selected')
       }
     }
   }
 
   clearSelection(): void {
     this.input.removeAttribute('aria-activedescendant')
     for (const el of this.list.querySelectorAll('[aria-selected="true"]')) {
-      el.setAttribute('aria-selected', 'false')
+      el.removeAttribute('aria-selected')
     }
+    this.indicateDefaultOption()
   }
 }
 
@@ -161,7 +177,7 @@ function commitWithElement(event: MouseEvent) {
 }
 
 function commit(input: HTMLTextAreaElement | HTMLInputElement, list: HTMLElement): boolean {
-  const target = list.querySelector<HTMLElement>('[aria-selected="true"]')
+  const target = list.querySelector<HTMLElement>('[aria-selected="true"], [data-combobox-option-default="true"]')
   if (!target) return false
   if (target.getAttribute('aria-disabled') === 'true') return true
   target.click()

test/test.js

@@ -54,7 +54,7 @@ describe('combobox-nav', function () {
       assert(!list.querySelector('[aria-selected=true]'), 'Nothing should be selected')
 
       combobox.destroy()
-      assert.equal(list.children[2].getAttribute('aria-selected'), 'false')
+      assert.equal(list.children[2].getAttribute('aria-selected'), null)
 
       assert(!input.hasAttribute('role'))
       assert(!input.hasAttribute('aria-expanded'))
@@ -204,7 +204,7 @@ describe('combobox-nav', function () {
 
       combobox.clearSelection()
 
-      assert.equal(options[0].getAttribute('aria-selected'), 'false')
+      assert.equal(options[0].getAttribute('aria-selected'), null)
       assert.equal(input.hasAttribute('aria-activedescendant'), false)
     })
 
@@ -226,4 +226,67 @@ describe('combobox-nav', function () {
       assert.equal(list.scrollTop, options[1].offsetTop)
     })
   })
+
+  describe('with defaulting to first option', function () {
+    let input
+    let list
+    let options
+    let combobox
+    beforeEach(function () {
+      document.body.innerHTML = `
+        <input type="text">
+        <ul role="listbox" id="list-id">
+          <li id="baymax" role="option">Baymax</li>
+          <li><del>BB-8</del></li>
+          <li id="hubot" role="option">Hubot</li>
+          <li id="r2-d2" role="option">R2-D2</li>
+          <li id="johnny-5" hidden role="option">Johnny 5</li>
+          <li id="wall-e" role="option" aria-disabled="true">Wall-E</li>
+          <li><a href="#link" role="option" id="link">Link</a></li>
+        </ul>
+      `
+      input = document.querySelector('input')
+      list = document.querySelector('ul')
+      options = document.querySelectorAll('[role=option]')
+      combobox = new Combobox(input, list, {defaultFirstOption: true})
+      combobox.start()
+    })
+
+    afterEach(function () {
+      combobox.destroy()
+      combobox = null
+      document.body.innerHTML = ''
+    })
+
+    it('indicates first option when started', () => {
+      assert.equal(document.querySelector('[data-combobox-option-default]'), options[0])
+      assert.equal(document.querySelectorAll('[data-combobox-option-default]').length, 1)
+    })
+
+    it('indicates first option when restarted', () => {
+      combobox.stop()
+      combobox.start()
+      assert.equal(document.querySelector('[data-combobox-option-default]'), options[0])
+    })
+
+    it('applies default option on Enter', () => {
+      let commits = 0
+      document.addEventListener('combobox-commit', () => commits++)
+
+      assert.equal(commits, 0)
+      press(input, 'Enter')
+      assert.equal(commits, 1)
+    })
+
+    it('clears default indication when navigating', () => {
+      combobox.navigate(1)
+      assert.equal(document.querySelectorAll('[data-combobox-option-default]').length, 0)
+    })
+
+    it('resets default indication when selection cleared', () => {
+      combobox.navigate(1)
+      combobox.clearSelection()
+      assert.equal(document.querySelectorAll('[data-combobox-option-default]').length, 1)
+    })
+  })
 })