rely on field name instead of field id

Author: gkogan

sup.js

@@ -1,7 +1,7 @@
 /*
 How to use this script:
 1. Add a hidden form field for each query string parameter you’d like to capture.
-   The field’s name and id should match the key of the query string parameter.
+   The field’s name should match the key of the query string parameter.
 2. Include the script on the page(s) where you’d like to use it, and activate it in your JavaScript:
    queryForm({reset: true});
    The value {reset: true} is optional. Including it will clear (reset) parameter values after a form is submitted.
@@ -23,6 +23,6 @@ var queryForm = function(settings){
   var hiddenFields = document.querySelectorAll("input[type=hidden]");
   for (var i=0; i<hiddenFields.length; i++) {
     var param = sessionStorage.getItem(hiddenFields[i].name);
-    if (param) document.getElementById(hiddenFields[i].name).value = param;
+    if (param) document.getElementsByName(hiddenFields[i].name)[0].value = param;
   }
 }