Ensure button plugin sets/removes active class correctly on page load (#28952)

* Ensure correct active class is set on button toggles/checkboxes/radios on page load

Sanity check, ensures that the UI visually matches the actual values/states of controls. Also ensures that if any autocomplete/autofill happened, this is visually accounted for
by having the correct class set.

Includes unit tests (and `autocomplete` has been removed from these as it's no longer necessary)

* Remove now unnecessary autocomplete attribute

As the attribute was there to force/ensure that the visual presentation matched the state, and this is now taken care of programmatically, there's no need to unnecessarily suppress autocomplete...let them autocomplete if they want to...

5 files changed, 120 insertions, 30 deletions

diff --git a/js/src/button.js b/js/src/button.js
index 622513701..70e6d3799 100644
--- a/js/src/button.js
+++ b/js/src/button.js
@@ -27,17 +27,20 @@ const ClassName = {
 }
 
 const Selector = {
-  DATA_TOGGLE_CARROT : '[data-toggle^="button"]',
-  DATA_TOGGLE        : '[data-toggle="buttons"]',
-  INPUT              : 'input:not([type="hidden"])',
-  ACTIVE             : '.active',
-  BUTTON             : '.btn'
+  DATA_TOGGLE_CARROT   : '[data-toggle^="button"]',
+  DATA_TOGGLES         : '[data-toggle="buttons"]',
+  DATA_TOGGLE          : '[data-toggle="button"]',
+  DATA_TOGGLES_BUTTONS : '[data-toggle="buttons"] .btn',
+  INPUT                : 'input:not([type="hidden"])',
+  ACTIVE               : '.active',
+  BUTTON               : '.btn'
 }
 
 const Event = {
   CLICK_DATA_API      : `click${EVENT_KEY}${DATA_API_KEY}`,
   FOCUS_BLUR_DATA_API : `focus${EVENT_KEY}${DATA_API_KEY} ` +
-                          `blur${EVENT_KEY}${DATA_API_KEY}`
+                          `blur${EVENT_KEY}${DATA_API_KEY}`,
+  LOAD_DATA_API       : `load${EVENT_KEY}${DATA_API_KEY}`
 }
 
 /**
@@ -63,7 +66,7 @@ class Button {
     let triggerChangeEvent = true
     let addAriaPressed = true
     const rootElement = $(this._element).closest(
-      Selector.DATA_TOGGLE
+      Selector.DATA_TOGGLES
     )[0]
 
     if (rootElement) {
@@ -167,6 +170,33 @@ $(document)
     $(button).toggleClass(ClassName.FOCUS, /^focus(in)?$/.test(event.type))
   })
 
+$(window).on(Event.LOAD_DATA_API, () => {
+  // ensure correct active class is set to match the controls' actual values/states
+
+  // find all checkboxes/readio buttons inside data-toggle groups
+  let buttons = [].slice.call(document.querySelectorAll(Selector.DATA_TOGGLES_BUTTONS))
+  for (let i = 0, len = buttons.length; i < len; i++) {
+    const button = buttons[i]
+    const input = button.querySelector(Selector.INPUT)
+    if (input.checked || input.hasAttribute('checked')) {
+      button.classList.add(ClassName.ACTIVE)
+    } else {
+      button.classList.remove(ClassName.ACTIVE)
+    }
+  }
+
+  // find all button toggles
+  buttons = [].slice.call(document.querySelectorAll(Selector.DATA_TOGGLE))
+  for (let i = 0, len = buttons.length; i < len; i++) {
+    const button = buttons[i]
+    if (button.getAttribute('aria-pressed') === 'true') {
+      button.classList.add(ClassName.ACTIVE)
+    } else {
+      button.classList.remove(ClassName.ACTIVE)
+    }
+  }
+})
+
 /**
  * ------------------------------------------------------------------------
  * jQuery
diff --git a/js/tests/unit/button.js b/js/tests/unit/button.js
index 324e94011..e5b349363 100644
--- a/js/tests/unit/button.js
+++ b/js/tests/unit/button.js
@@ -100,13 +100,73 @@ $(function () {
     assert.strictEqual($btn.attr('aria-pressed'), 'true', 'btn aria-pressed state is true')
   })
 
+  QUnit.test('should assign active class on page load to buttons with aria-pressed="true"', function (assert) {
+    assert.expect(1)
+    var done = assert.async()
+    var $btn = $('<button class="btn" data-toggle="button" aria-pressed="true">mdo</button>')
+    $btn.appendTo('#qunit-fixture')
+    $(window).trigger($.Event('load'))
+    setTimeout(function () {
+      assert.ok($btn.hasClass('active'), 'button with aria-pressed="true" has been given class active')
+      done()
+    }, 5)
+  })
+
+  QUnit.test('should assign active class on page load to button checkbox with checked attribute', function (assert) {
+    assert.expect(1)
+    var done = assert.async()
+    var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
+      '<label class="btn btn-primary">' +
+      '<input type="checkbox" id="radio" checked> Checkbox' +
+      '</label>' +
+      '</div>'
+    var $group = $(groupHTML).appendTo('#qunit-fixture')
+    var $btn = $group.children().eq(0)
+
+    $(window).trigger($.Event('load'))
+    setTimeout(function () {
+      assert.ok($btn.hasClass('active'), 'checked checkbox button has been given class active')
+      done()
+    }, 5)
+  })
+
+  QUnit.test('should remove active class on page load from buttons without aria-pressed="true"', function (assert) {
+    assert.expect(1)
+    var done = assert.async()
+    var $btn = $('<button class="btn active" data-toggle="button" aria-pressed="false">mdo</button>')
+    $btn.appendTo('#qunit-fixture')
+    $(window).trigger($.Event('load'))
+    setTimeout(function () {
+      assert.ok(!$btn.hasClass('active'), 'button without aria-pressed="true" has had active class removed')
+      done()
+    }, 5)
+  })
+
+  QUnit.test('should remove active class on page load from button checkbox without checked attribute', function (assert) {
+    assert.expect(1)
+    var done = assert.async()
+    var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
+      '<label class="btn btn-primary active">' +
+      '<input type="checkbox" id="radio"> Checkbox' +
+      '</label>' +
+      '</div>'
+    var $group = $(groupHTML).appendTo('#qunit-fixture')
+    var $btn = $group.children().eq(0)
+
+    $(window).trigger($.Event('load'))
+    setTimeout(function () {
+      assert.ok(!$btn.hasClass('active'), 'unchecked checkbox button has had active class removed')
+      done()
+    }, 5)
+  })
+
   QUnit.test('should trigger input change event when toggled button has input field', function (assert) {
     assert.expect(1)
     var done = assert.async()
 
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
       '<label class="btn btn-primary">' +
-      '<input type="radio" id="radio" autocomplete="off">Radio' +
+      '<input type="radio" id="radio">Radio' +
       '</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
@@ -158,8 +218,8 @@ $(function () {
   QUnit.test('should not add aria-pressed on labels for radio/checkbox inputs in a data-toggle="buttons" group', function (assert) {
     assert.expect(2)
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
-      '<label class="btn btn-primary"><input type="checkbox" autocomplete="off"> Checkbox</label>' +
-      '<label class="btn btn-primary"><input type="radio" name="options" autocomplete="off"> Radio</label>' +
+      '<label class="btn btn-primary"><input type="checkbox"> Checkbox</label>' +
+      '<label class="btn btn-primary"><input type="radio" name="options"> Radio</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
 
@@ -177,7 +237,7 @@ $(function () {
     assert.expect(4)
     var groupHTML = '<div class="btn-group disabled" data-toggle="buttons" aria-disabled="true" disabled>' +
       '<label class="btn btn-danger disabled">' +
-      '<input type="checkbox" aria-disabled="true" autocomplete="off" disabled>' +
+      '<input type="checkbox" aria-disabled="true" disabled>' +
       '</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
@@ -196,7 +256,7 @@ $(function () {
     assert.expect(4)
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
       '<label class="btn btn-danger">' +
-      '<input type="checkbox" autocomplete="off" disabled>' +
+      '<input type="checkbox" disabled>' +
       '</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
@@ -215,7 +275,7 @@ $(function () {
     assert.expect(4)
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
       '<label class="btn">' +
-      '<input type="checkbox" autocomplete="off">' +
+      '<input type="checkbox">' +
       '</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
@@ -234,7 +294,7 @@ $(function () {
     assert.expect(4)
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
       '<div class="btn">' +
-      '<input type="checkbox" autocomplete="off" aria-label="Check">' +
+      '<input type="checkbox" aria-label="Check">' +
       '</div>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
@@ -253,7 +313,7 @@ $(function () {
     assert.expect(4)
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
       '<label class="btn">' +
-      '<input type="checkbox" autocomplete="off">' +
+      '<input type="checkbox">' +
       '</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
@@ -272,7 +332,7 @@ $(function () {
     assert.expect(2)
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
       '<label class="btn">' +
-      '<input type="hidden" autocomplete="off">' +
+      '<input type="hidden">' +
       '</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
@@ -289,7 +349,7 @@ $(function () {
     assert.expect(2)
     var groupHTML = '<div class="btn-group" data-toggle="buttons">' +
       '<label class="btn">' +
-      '<input type="text" autocomplete="off">' +
+      '<input type="text">' +
       '</label>' +
       '</div>'
     var $group = $(groupHTML).appendTo('#qunit-fixture')
diff --git a/js/tests/visual/button.html b/js/tests/visual/button.html
index b7ba7964d..183a6ad2c 100644
--- a/js/tests/visual/button.html
+++ b/js/tests/visual/button.html
@@ -10,7 +10,7 @@
     <div class="container">
       <h1>Button <small>Bootstrap Visual Test</small></h1>
 
-      <button type="button" class="btn btn-primary" data-toggle="button" aria-pressed="false" autocomplete="off">
+      <button type="button" class="btn btn-primary" data-toggle="button" aria-pressed="false">
         Single toggle
       </button>
 
@@ -19,13 +19,13 @@
 
       <div class="btn-group" data-toggle="buttons">
         <label class="btn btn-primary active">
-          <input type="checkbox" checked autocomplete="off"> Checkbox 1 (pre-checked)
+          <input type="checkbox" checked> Checkbox 1 (pre-checked)
         </label>
         <label class="btn btn-primary">
-          <input type="checkbox" autocomplete="off"> Checkbox 2
+          <input type="checkbox"> Checkbox 2
         </label>
         <label class="btn btn-primary">
-          <input type="checkbox" autocomplete="off"> Checkbox 3
+          <input type="checkbox"> Checkbox 3
         </label>
       </div>
 
@@ -33,13 +33,13 @@
 
       <div class="btn-group" data-toggle="buttons">
         <label class="btn btn-primary active">
-          <input type="radio" name="options" id="option1" autocomplete="off" checked> Radio 1 (preselected)
+          <input type="radio" name="options" id="option1" checked> Radio 1 (preselected)
         </label>
         <label class="btn btn-primary">
-          <input type="radio" name="options" id="option2" autocomplete="off"> Radio 2
+          <input type="radio" name="options" id="option2"> Radio 2
         </label>
         <label class="btn btn-primary">
-          <input type="radio" name="options" id="option3" autocomplete="off"> Radio 3
+          <input type="radio" name="options" id="option3"> Radio 3
         </label>
       </div>
     </div>
diff --git a/site/docs/4.3/components/buttons.md b/site/docs/4.3/components/buttons.md
index 118679752..f26a54090 100644
--- a/site/docs/4.3/components/buttons.md
+++ b/site/docs/4.3/components/buttons.md
@@ -117,7 +117,7 @@ Do more with buttons. Control button states or create groups of buttons for more
 Add `data-toggle="button"` to toggle a button's `active` state. If you're pre-toggling a button, you must manually add the `.active` class **and** `aria-pressed="true"` to the `<button>`.
 
 {% capture example %}
-<button type="button" class="btn btn-primary" data-toggle="button" aria-pressed="false" autocomplete="off">
+<button type="button" class="btn btn-primary" data-toggle="button" aria-pressed="false">
   Single toggle
 </button>
 {% endcapture %}
@@ -134,7 +134,7 @@ Note that pre-checked buttons require you to manually add the `.active` class to
 {% capture example %}
 <div class="btn-group-toggle" data-toggle="buttons">
   <label class="btn btn-secondary active">
-    <input type="checkbox" checked autocomplete="off"> Checked
+    <input type="checkbox" checked> Checked
   </label>
 </div>
 {% endcapture %}
@@ -143,13 +143,13 @@ Note that pre-checked buttons require you to manually add the `.active` class to
 {% capture example %}
 <div class="btn-group btn-group-toggle" data-toggle="buttons">
   <label class="btn btn-secondary active">
-    <input type="radio" name="options" id="option1" autocomplete="off" checked> Active
+    <input type="radio" name="options" id="option1" checked> Active
   </label>
   <label class="btn btn-secondary">
-    <input type="radio" name="options" id="option2" autocomplete="off"> Radio
+    <input type="radio" name="options" id="option2"> Radio
   </label>
   <label class="btn btn-secondary">
-    <input type="radio" name="options" id="option3" autocomplete="off"> Radio
+    <input type="radio" name="options" id="option3"> Radio
   </label>
 </div>
 {% endcapture %}
diff --git a/site/docs/4.3/components/progress.md b/site/docs/4.3/components/progress.md
index e342b06d9..7c42aec3e 100644
--- a/site/docs/4.3/components/progress.md
+++ b/site/docs/4.3/components/progress.md
@@ -134,7 +134,7 @@ The striped gradient can also be animated. Add `.progress-bar-animated` to `.pro
   <div class="progress">
     <div class="progress-bar progress-bar-striped" role="progressbar" aria-valuenow="75" aria-valuemin="0" aria-valuemax="100" style="width: 75%"></div>
   </div>
-  <button type="button" class="btn btn-secondary bd-toggle-animated-progress" data-toggle="button" aria-pressed="false" autocomplete="off">
+  <button type="button" class="btn btn-secondary bd-toggle-animated-progress" data-toggle="button" aria-pressed="false">
     Toggle animation
   </button>
 </div>