diff --git a/js/TDZ.js b/js/TDZ.js
new file mode 100644
index 0000000000000000000000000000000000000000..8a6101be23f9ec3e76afc0611f074b46ca2191da
--- /dev/null
+++ b/js/TDZ.js
@@ -0,0 +1,6 @@
+let value1 = 'outer value'
+
+(function() {
+  console.log(value1) // ReferenceError
+  let value1 = 'inner value' // defined value1
+}())
\ No newline at end of file