Add .map to list facet as its needed frequently enough

lib/components/c_facets/List.js

@@ -41,6 +41,7 @@ _.extendProto(List, {
     removeItem: List$removeItem,
     extractItem: List$extractItem,
     each: List$each,
+    map: List$map,
     _setItem: List$_setItem,
     _removeItem: List$_removeItem,
     _addItem: List$_addItem,
@@ -103,8 +104,8 @@ function onChildrenBound() {
             item.item.setIndex(index);
         });
     }
-    
-    // Component must have one child with an Item facet 
+
+    // Component must have one child with an Item facet
     if (! foundItem) throw new Error('No child component has Item facet');
 
     this.list.itemSample = foundItem;
@@ -125,7 +126,7 @@ function onChildrenBound() {
 
 function List$_createCacheTemplate() {
     if (!this.itemSample) return false;
-    
+
     var itemSample = this.itemSample;
 
     // create item template to insert many items at once
@@ -136,7 +137,7 @@ function List$_createCacheTemplate() {
     attr.el = itemElCopy;
     attr.decorate();
 
-    var itemsTemplateStr = 
+    var itemsTemplateStr =
           '{{ var i = it.count; while(i--) { }}'
         + itemElCopy.outerHTML
         + '{{ } }}';
@@ -247,7 +248,7 @@ function _updateItemsIndexes(fromIndex, toIndex) {
 
 function List$addItems(count, index) { // ,... items data
     var itemsData = _.slice(arguments, 2);
-    if (itemsData.length < count) 
+    if (itemsData.length < count)
         itemsData.concat(_.repeat(count - itemsData.length, {}));
     var spliceArgs = [index, 0].concat(itemsData);
     var dataFacet = this.owner.data;
@@ -348,7 +349,7 @@ function List$extractItem(index) {
 /**
  * List facet instance method
  * Removes item, returns the removed item that is destroyed by default.
- * 
+ *
  * @param  {Number} index item index
  * @param  {Boolean} doDestroyItem optional false to prevent item destruction, true by default
  * @return {Component}
@@ -420,6 +421,14 @@ function List$each(callback, thisArg) {
 }
 
 
+function List$map(callback, thisArg) {
+    return this._listItems.map(function(item, index) {
+        if (item) return callback.apply(this, arguments); // passes item, index to callback
+        else logger.warn('List$map: item', index, 'is undefined');
+    }, thisArg || this);
+}
+
+
 /**
  * Facet instance method
  * Destroys the list