add activeTab, selectedTabIndex props

Author: keithamus

src/tab-container-element.ts

@@ -107,6 +107,10 @@ export class TabContainerElement extends HTMLElement {
     )
   }
 
+  get activeTab() {
+    return this.#tabs[this.selectedTabIndex]
+  }
+
   get activePanel() {
     return this.#panelSlot.assignedNodes()[0] as HTMLElement
   }
@@ -181,7 +185,7 @@ export class TabContainerElement extends HTMLElement {
     const tabs = this.#tabs
     if (!tabs.includes(tab as HTMLElement)) return
 
-    const currentIndex = tabs.indexOf(tabs.find(e => e.matches('[aria-selected="true"]'))!)
+    const currentIndex = this.selectedTabIndex
     const vertical = tab.closest('[role="tablist"]')?.getAttribute('aria-orientation') === 'vertical'
     const prevTab = event.code === 'ArrowLeft' || (vertical && event.code === 'ArrowUp')
     const nextTab = event.code === 'ArrowRight' || (vertical && event.code === 'ArrowDown')
@@ -218,6 +222,14 @@ export class TabContainerElement extends HTMLElement {
     }
   }
 
+  get selectedTabIndex(): number {
+    return this.#tabs.findIndex(el => el.matches('[aria-selected=true]'))
+  }
+
+  set selectedTabIndex(i: number) {
+    this.selectTab(i)
+  }
+
   selectTab(index: number): void {
     if (!this.#setupComplete) {
       const tabListSlot = this.#tabListSlot
@@ -276,7 +288,7 @@ export class TabContainerElement extends HTMLElement {
         for (const el of afterSlotted) el.setAttribute('slot', 'after-panels')
       }
       const defaultTab = Number(this.getAttribute('default-tab') || -1)
-      const defaultIndex = defaultTab >= 0 ? defaultTab : this.#tabs.findIndex(el => el.matches('[aria-selected=true]'))
+      const defaultIndex = defaultTab >= 0 ? defaultTab : this.selectedTabIndex
       index = index >= 0 ? index : Math.max(0, defaultIndex)
     }
 

test/test.js

@@ -162,6 +162,8 @@ describe('tab-container', function () {
         'change events point to second panel',
       )
       assert.equal(document.activeElement, tabs[1])
+      assert.equal(tabContainer.activeTab, tabs[1])
+      assert.equal(tabContainer.selectedTabIndex, 1)
     })
 
     it('keyboard shortcuts work and `tab-container-changed` events are dispatched', function () {
@@ -187,6 +189,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [true, false, false], 'First tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [false, true, true], 'First panel is visible')
       assert.equal(document.activeElement, tabs[0])
+      assert.equal(tabContainer.activeTab, tabs[0])
+      assert.equal(tabContainer.selectedTabIndex, 0)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -280,6 +284,8 @@ describe('tab-container', function () {
         'change events point to second panel',
       )
       assert.equal(document.activeElement, tabs[1])
+      assert.equal(tabContainer.activeTab, tabs[1])
+      assert.equal(tabContainer.selectedTabIndex, 1)
     })
 
     it('result in noop, when selectTab receives out of bounds index', function () {
@@ -417,6 +423,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [false, false, true], 'Third tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [true, true, false], 'Third panel is visible')
       assert.equal(document.activeElement, tabs[2])
+      assert.equal(tabContainer.activeTab, tabs[2])
+      assert.equal(tabContainer.selectedTabIndex, 2)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -439,6 +447,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [true, false, false], 'First tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [false, true, true], 'First panel is visible')
       assert.equal(document.activeElement, tabs[0])
+      assert.equal(tabContainer.activeTab, tabs[0])
+      assert.equal(tabContainer.selectedTabIndex, 0)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -461,6 +471,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [false, true, false], 'Second tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [true, false, true], 'Second panel is visible')
       assert.equal(document.activeElement, tabs[1])
+      assert.equal(tabContainer.activeTab, tabs[1])
+      assert.equal(tabContainer.selectedTabIndex, 1)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -483,6 +495,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [false, false, true], 'Third tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [true, true, false], 'Third panel is visible')
       assert.equal(document.activeElement, tabs[2])
+      assert.equal(tabContainer.activeTab, tabs[2])
+      assert.equal(tabContainer.selectedTabIndex, 2)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -506,6 +520,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [false, false, true], 'Third tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [true, true, false], 'Third panel is visible')
       assert.equal(document.activeElement, tabs[2])
+      assert.equal(tabContainer.activetab, tabs[2])
+      assert.equal(tabContainer.selectedTabIndex, 2)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -528,6 +544,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [true, false, false], 'First tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [false, true, true], 'First panel is visible')
       assert.equal(document.activeElement, tabs[0])
+      assert.equal(tabContainer.activeTab, tabs[0])
+      assert.equal(tabContainer.selectedTabIndex, 0)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -550,6 +568,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [false, true, false], 'Second tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [true, false, true], 'Second panel is visible')
       assert.equal(document.activeElement, tabs[1])
+      assert.equal(tabContainer.activetab, tabs[1])
+      assert.equal(tabContainer.selectedTabIndex, 1)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),
@@ -572,6 +592,8 @@ describe('tab-container', function () {
       assert.deepStrictEqual(tabs.map(isSelected), [false, false, true], 'Third tab is selected')
       assert.deepStrictEqual(panels.map(isHidden), [true, true, false], 'Third panel is visible')
       assert.equal(document.activeElement, tabs[2])
+      assert.equal(tabContainer.activetab, tabs[2])
+      assert.equal(tabContainer.selectedTabIndex, 2)
       assert.equal(events.length, 2, 'tab-container-change(d) called')
       assert.deepStrictEqual(
         events.map(e => e.type),