Set enabled similar to preventDefault and preventEnterSubmit directives

src/Umbraco.Web.UI.Client/src/common/directives/components/forms/umbautofocus.directive.js

@@ -1,18 +1,27 @@
 angular.module("umbraco.directives")
     .directive('umbAutoFocus', function($timeout) {
 
-        return function(scope, element, attr){
+        return function (scope, element, attrs) {
             var update = function() {
                 //if it uses its default naming
-                if(element.val() === "" || attr.focusOnFilled){
+                if (element.val() === "" || attrs.focusOnFilled){
                     element.trigger("focus");
                 }
             };
 
-            if (attr.umbAutoFocus !== "false") {
+            var enabled = true;
+            //check if there's a value for the attribute, if there is and it's false then we conditionally don't
+            //use auto focus.
+            if (attrs.umbAutoFocus) {
+                attrs.$observe("umbAutoFocus", function (newVal) {
+                    enabled = (newVal === "false" || newVal === 0 || newVal === false) ? false : true;
+                });
+            }
+
+            if (enabled) {
                 $timeout(function() {
                     update();
                 });
             }
-    };
+        };
 });