fix js when regexp doesn't match

Author: lest

vendor/assets/javascripts/jquery_nested_form.js

@@ -17,9 +17,9 @@
       var context = ($(link).closest('.fields').closestChild('input, textarea, select').eq(0).attr('name') || '').replace(/\[[a-z_]+\]$/, '');
 
       // If the parent has no inputs we need to strip off the last pair
-      var current = content.match(new RegExp('\\[([a-z_]+)\\]\\[new_' + assoc + '\\]'))[1];
+      var current = content.match(new RegExp('\\[([a-z_]+)\\]\\[new_' + assoc + '\\]'));
       if (current) {
-        context = context.replace(new RegExp('\\['+current+'\\]\\[(new_)?\\d+\\]$'), '');
+        context = context.replace(new RegExp('\\[' + current[1] + '\\]\\[(new_)?\\d+\\]$'), '');
       }
 
       // context will be something like this for a brand new form:

vendor/assets/javascripts/prototype_nested_form.js

@@ -11,9 +11,9 @@ document.observe('click', function(e, el) {
     var context = (el.getOffsetParent('.fields').firstDescendant().readAttribute('name') || '').replace(/\[[a-z_]+\]$/, '');
 
     // If the parent has no inputs we need to strip off the last pair
-    var current = content.match(new RegExp('\\[([a-z_]+)\\]\\[new_' + assoc + '\\]'))[1];
+    var current = content.match(new RegExp('\\[([a-z_]+)\\]\\[new_' + assoc + '\\]'));
     if (current) {
-      context = context.replace(new RegExp('\\['+current+'\\]\\[(new_)?\\d+\\]$'), '');
+      context = context.replace(new RegExp('\\[' + current[1] + '\\]\\[(new_)?\\d+\\]$'), '');
     }
 
     // context will be something like this for a brand new form: