feat(): templateOptions.className

equivalent to ng-class on ng-model.

It can be string, array or just an expression

src/runs/class-name.js

@@ -0,0 +1,12 @@
+import { ngModelAttrsTransformer } from './../helpers/index.js';
+
+export default (formlyConfigProvider) => {
+  // add only step attribute because min and max are both built-in
+  formlyConfigProvider.extras.fieldTransform.push((fields) => {
+    return ngModelAttrsTransformer(fields, (field) => (
+      field.templateOptions && typeof field.templateOptions.className !== 'undefined'
+    ), 'className', {
+      bound: 'ng-class'
+    });
+  });
+};

src/runs/index.js

@@ -1,3 +1,4 @@
+import className from './class-name';
 import theme from './theme';
 
-export default [theme];
+export default [className, theme];