StepUi: Accept and return vanilla DOM content

This encapsulates the use of jQuery which will eventually be entirely
eliminated.

src/ui/step/StepUi.js

@@ -25,6 +25,9 @@
  *       - ElementStyler;
  *       - BucketDataValidator.
  *   - Global references (e.g. jQuery) must be removed.
+ *   - jQuery must be eliminated.
+ *     - The public API now accepts and returns vanilla DOM content, so at
+ *       least it's encapsulated now.
  *   - Checkbox-specific logic must be extracted.
  *   - This class is doing too much.
  * @end needsLove
@@ -235,13 +238,14 @@ module.exports = Class( 'StepUi' )
     /**
      * Sets content to be displayed
      *
-     * @param {jQuery} $content content to display
+     * @param {HTMLElement} content content to display
      *
      * @return {StepUi} self
      */
-    'public setContent': function( $content )
+    'public setContent': function( content )
     {
-        this.$content = $content;
+        // TODO: transition away from jQuery
+        this.$content = $( content );
 
         this._processAnswerFields();
 
@@ -263,11 +267,11 @@ module.exports = Class( 'StepUi' )
     /**
      * Returns the generated step content as a jQuery object
      *
-     * @return {jQuery} generated step content
+     * @return {HTMLElement} generated step content
      */
-    getContent: function()
+    'virtual getContent': function()
     {
-        return this.$content;
+        return this.$content[ 0 ];
     },
 
 

src/ui/step/StepUiBuilder.js

@@ -160,10 +160,11 @@ module.exports = Class( 'StepUiBuilder' )
         }
 
         // enclose it in a div so that we have a single element we can query,
-        // making our lives much easier
+        // making our lives much easier (TODO: this is transitional code
+        // moving from jQuery to vanilla DOM)
         ui.setContent(
             $( '<div class="step-groups" />')
-                .append( $( data.content.html ) )
+                .append( $( data.content.html ) )[ 0 ]
         );
 
         // free the content from memory, as it's no longer needed (we don't need
@@ -203,8 +204,10 @@ module.exports = Class( 'StepUiBuilder' )
 
             step = ui.getStep();
 
+        var $content = $( ui.getContent() );
+
         // instantiate a group object for each of the groups within this step
-        var $groups = ( ui.getContent().find( '.stepGroup' ) ).each( function()
+        var $groups = $content.find( '.stepGroup' ).each( function()
         {
             group    = _self._groupBuilder( $( this ), _self._elementStyler );
             group_id = group.getGroupId();