New: Added use helper (fixes #504) (#505)

* New: Added use helper (fixes #504)

* Missing import

Author: oliverfoster

js/helpers.js

@@ -1,5 +1,6 @@
 import Adapt from 'core/js/adapt';
 import a11y from 'core/js/a11y';
+import data from 'core/js/data';
 import logging from './logging';
 
 const helpers = {
@@ -67,6 +68,14 @@ const helpers = {
     }
   },
 
+  use(id, block) {
+    if (!block.fn) return;
+    try {
+      const model = data.findById(id);
+      return block.fn(model.toJSON());
+    } catch (err) {}
+  },
+
   /**
    * Equivalent to:
    *  if (conditionA || conditionB)