diff --git a/static/main.js b/static/main.js
index e2b029c..e83a584 100644
--- a/static/main.js
+++ b/static/main.js
@@ -45,16 +45,15 @@
     var paper_id = $("#paper_id");
     if ($('#author').is(":checked")) {
         paper_id.removeAttr('disabled');
-        paper_id.attr('placeholder', '0');
         paper_id.attr('pattern', '\\d{1,4}');
         paper_id.attr('required', 'required');
-        //if (paper_id.attr('oldval').match(/^\\d{4}$/)) {
-        //    paper_id.val(paper_id.attr('oldval'));
-        //}
+        val = paper_id.val();
+        if (!x.match(/^\d{1,4}$/)) {
+            paper_id.val('');
+        }
     } else {
-        paper_id.attr('oldval', paper_id.val());
-        paper_id.val('');
         paper_id.attr('disabled', 'disabled');
+        paper_id.val('');
         paper_id.removeAttr('placeholder');
         paper_id.removeAttr('pattern');
         paper_id.removeAttr('required');