diff --git a/5.4ArrayMethod/t.js b/5.4ArrayMethod/t.js
index 8af9b03..26a63cc 100644
--- a/5.4ArrayMethod/t.js
+++ b/5.4ArrayMethod/t.js
@@ -33,3 +33,5 @@ someUsers = users.filter(function(item, index, array){
 console.log(someUsers);
 
 // arr.map(fn)
+let lengths = array.map(item=>item.length);
+alert(lengths);
\ No newline at end of file