Add option to auto navigate to the first item on open

src/index.ts

@@ -1,9 +1,12 @@
 export type ComboboxSettings = {
   tabInsertsSuggestions?: boolean
-  defaultFirstOption?: boolean
+  firstOptionSelectionMode?: FirstOptionSelectionMode
   scrollIntoViewOptions?: boolean | ScrollIntoViewOptions
 }
 
+// Indicates the default behaviour for the first option when the list is shown.
+export type FirstOptionSelectionMode = 'none' | 'selected' | 'focused'
+
 export default class Combobox {
   isComposing: boolean
   list: HTMLElement
@@ -13,18 +16,18 @@ export default class Combobox {
   inputHandler: (event: Event) => void
   ctrlBindings: boolean
   tabInsertsSuggestions: boolean
-  defaultFirstOption: boolean
+  firstOptionSelectionMode: FirstOptionSelectionMode
   scrollIntoViewOptions?: boolean | ScrollIntoViewOptions
 
   constructor(
     input: HTMLTextAreaElement | HTMLInputElement,
     list: HTMLElement,
-    {tabInsertsSuggestions, defaultFirstOption, scrollIntoViewOptions}: ComboboxSettings = {},
+    {tabInsertsSuggestions, firstOptionSelectionMode, scrollIntoViewOptions}: ComboboxSettings = {},
   ) {
     this.input = input
     this.list = list
     this.tabInsertsSuggestions = tabInsertsSuggestions ?? true
-    this.defaultFirstOption = defaultFirstOption ?? false
+    this.firstOptionSelectionMode = firstOptionSelectionMode ?? 'none'
     this.scrollIntoViewOptions = scrollIntoViewOptions ?? {block: 'nearest', inline: 'nearest'}
 
     this.isComposing = false
@@ -64,6 +67,7 @@ export default class Combobox {
     ;(this.input as HTMLElement).addEventListener('keydown', this.keyboardEventHandler)
     this.list.addEventListener('click', commitWithElement)
     this.indicateDefaultOption()
+    this.focusDefaultOptionIfNeeded()
   }
 
   stop(): void {
@@ -77,13 +81,19 @@ export default class Combobox {
   }
 
   indicateDefaultOption(): void {
-    if (this.defaultFirstOption) {
+    if (this.firstOptionSelectionMode === 'selected') {
       Array.from(this.list.querySelectorAll<HTMLElement>('[role="option"]:not([aria-disabled="true"])'))
         .filter(visible)[0]
         ?.setAttribute('data-combobox-option-default', 'true')
     }
   }
 
+  focusDefaultOptionIfNeeded(): void {
+    if (this.firstOptionSelectionMode === 'focused') {
+      this.navigate(1)
+    }
+  }
+
   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)

test/test.js

@@ -263,7 +263,7 @@ describe('combobox-nav', function () {
       input = document.querySelector('input')
       list = document.querySelector('ul')
       options = document.querySelectorAll('[role=option]')
-      combobox = new Combobox(input, list, {defaultFirstOption: true})
+      combobox = new Combobox(input, list, {firstOptionSelectionMode: 'selected'})
       combobox.start()
     })
 
@@ -276,6 +276,7 @@ describe('combobox-nav', function () {
     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)
+      assert.equal(list.children[0].getAttribute('aria-selected'), null)
     })
 
     it('indicates first option when restarted', () => {
@@ -311,4 +312,63 @@ describe('combobox-nav', function () {
       })
     })
   })
+
+  describe('with defaulting to focusing the first option', function () {
+    let input
+    let list
+    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')
+      combobox = new Combobox(input, list, {firstOptionSelectionMode: 'focused'})
+      combobox.start()
+    })
+
+    afterEach(function () {
+      combobox.destroy()
+      combobox = null
+      document.body.innerHTML = ''
+    })
+
+    it('focuses first option when started', () => {
+      // Does not set the default attribute
+      assert.equal(document.querySelectorAll('[data-combobox-option-default]').length, 0)
+      // Item is correctly selected
+      assert.equal(list.children[0].getAttribute('aria-selected'), 'true')
+    })
+
+    it('indicates first option when restarted', () => {
+      combobox.stop()
+      combobox.start()
+      assert.equal(list.children[0].getAttribute('aria-selected'), 'true')
+    })
+
+    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('does not error when no options are visible', () => {
+      assert.doesNotThrow(() => {
+        document.getElementById('list-id').style.display = 'none'
+        combobox.clearSelection()
+      })
+    })
+  })
 })