refactor(MultiSelect): fix eslint warnings

Author: mrholek

js/src/multi-select.js

@@ -286,7 +286,7 @@ class MultiSelect extends BaseComponent {
   }
 
   _getClassNames() {
-    return [...this._element.classList.value.split(' ')]
+    return this._element.classList.value.split(' ')
   }
 
   _getOptions(node = this._element) {
@@ -355,12 +355,7 @@ class MultiSelect extends BaseComponent {
 
   _createNativeOptions(parentElement, options) {
     for (const option of options) {
-      if ((typeof option.options !== 'undefined')) {
-        const optgroup = document.createElement('optgroup')
-        optgroup.label = option.label
-        this._createNativeOptions(optgroup, option.options)
-        parentElement.append(optgroup)
-      } else {
+      if ((typeof option.options === 'undefined')) {
         const opt = document.createElement('OPTION')
         opt.value = option.value
 
@@ -374,6 +369,11 @@ class MultiSelect extends BaseComponent {
 
         opt.innerHTML = option.text
         parentElement.append(opt)
+      } else {
+        const optgroup = document.createElement('optgroup')
+        optgroup.label = option.label
+        this._createNativeOptions(optgroup, option.options)
+        parentElement.append(optgroup)
       }
     }
   }