diff --git a/index.html b/index.html
index 5cfebac9a1..0e494734f5 100644
--- a/index.html
+++ b/index.html
@@ -22,6 +22,10 @@
 <script src="asciidoctor/asciidoctor.js"></script>
 <script>
     function renderRule(/*string*/ruleId) {
+      if (ruleId === "") {
+        document.getElementById("div-result").innerHTML = "";
+        return;
+      }
       const asciiDoctor = Asciidoctor();
       const rulesDir = parentDirectory(location.href) + "rules";
       const ruleFile = rulesDir + "/" + ruleId + "/rule.adoc";