feature: Remove support for setting nonstandard attributes as props

src/js/slider/slider.js

@@ -133,8 +133,7 @@ class Slider extends Component {
       'role': 'slider',
       'aria-valuenow': 0,
       'aria-valuemin': 0,
-      'aria-valuemax': 100,
-      'tabIndex': 0
+      'aria-valuemax': 100
     }, attributes);
 
     return super.createEl(type, props, attributes);

src/js/utils/dom.js

@@ -153,18 +153,9 @@ export function createEl(tagName = 'div', properties = {}, attributes = {}, cont
   Object.getOwnPropertyNames(properties).forEach(function(propName) {
     const val = properties[propName];
 
-    // See #2176
-    // We originally were accepting both properties and attributes in the
-    // same object, but that doesn't work so well.
-    if (propName.indexOf('aria-') !== -1 || propName === 'role' || propName === 'type') {
-      log.warn('Setting attributes in the second argument of createEl()\n' +
-               'has been deprecated. Use the third argument instead.\n' +
-               `createEl(type, properties, attributes). Attempting to set ${propName} to ${val}.`);
-      el.setAttribute(propName, val);
-
     // Handle textContent since it's not supported everywhere and we have a
     // method for it.
-    } else if (propName === 'textContent') {
+    if (propName === 'textContent') {
       textContent(el, val);
     } else if (el[propName] !== val || propName === 'tabIndex') {
       el[propName] = val;

test/unit/utils/dom.test.js

@@ -30,13 +30,26 @@ QUnit.test('should create an element, supporting textContent', function(assert)
   }
 });
 
+QUnit.test('should create an element with tabIndex prop', function(assert) {
+  const span = Dom.createEl('span', {tabIndex: '5'});
+
+  assert.strictEqual(span.tabIndex, 5);
+});
+
 QUnit.test('should create an element with content', function(assert) {
   const span = Dom.createEl('span');
   const div = Dom.createEl('div', undefined, undefined, span);
 
   assert.strictEqual(div.firstChild, span);
 });
 
+QUnit.test('should be able to set standard props as attributes, and vice versa, on a created element', function(assert) {
+  const span = Dom.createEl('span', {className: 'bar'}, {id: 'foo'});
+
+  assert.strictEqual(span.getAttribute('class'), 'bar');
+  assert.strictEqual(span.id, 'foo');
+});
+
 QUnit.test('should insert an element first in another', function(assert) {
   const el1 = document.createElement('div');
   const el2 = document.createElement('div');