diff --git a/files/en-us/web/javascript/guide/grammar_and_types/index.md b/files/en-us/web/javascript/guide/grammar_and_types/index.md
index 71a7e3581c247da..b1d332cfe67b576 100644
--- a/files/en-us/web/javascript/guide/grammar_and_types/index.md
+++ b/files/en-us/web/javascript/guide/grammar_and_types/index.md
@@ -517,6 +517,16 @@ Object literals support a range of shorthand syntaxes that include setting the p
 Together, these also bring object literals and class declarations closer together, and allow object-based design to benefit from some of the same conveniences.
 
 ```js
+// If `theProtoObj` and `handler` are not declared,
+// the code will throw a ReferenceError:
+// "theProtoObj is not defined" or "handler is not defined"
+
+const theProtoObj = {
+    /*The proto Object*/
+};
+const handler = {
+    /*Handler*/
+}
 const obj = {
   // __proto__
   __proto__: theProtoObj,