From 95550ca928b5e1a31397edb1d9d044ce2531560c Mon Sep 17 00:00:00 2001
From: "jason.zhu" <jason.zhu@xero.com>
Date: Wed, 12 May 2021 11:46:43 +1000
Subject: [PATCH] Finished Module 1: Writing modular code with functions

---
 1_writing_modular_code_with_functions.md | 21 +++++++++++++++++++--
 1 file changed, 19 insertions(+), 2 deletions(-)

diff --git a/1_writing_modular_code_with_functions.md b/1_writing_modular_code_with_functions.md
index 612ffe0..6d831cd 100644
--- a/1_writing_modular_code_with_functions.md
+++ b/1_writing_modular_code_with_functions.md
@@ -118,7 +118,7 @@ where:
 
 ## How Closure Work
 
-Local variable within function has short life span, as it's out of scope as function finish execution. But sometime we want to hold the variable (e.g. `counter` within function)
+Local variable within function has short life span, as it's out of scope as function finish execution. But sometime we want to hold the variable (e.g. `counter` within function), we can use closure.
 
 e.g. w/o closure
 
@@ -139,8 +139,25 @@ let greeting = (function() {
     let getMessage = function(){
         return message;
     };
+    // Use closure
     return {
         getMessage: getMessage,
     }
-})
+})();
+console.log(greeting.getMessage()); // Hello
+```
+
+e.g. closure used for counter
+
+```javascript
+function setupCounter(val){
+    return function counter() {
+        return val++;
+    }
+}
+let counter1 = setupCounter(0);
+console.log(counter1()); // 0
+console.log(counter1()); // 1
+let counter2 = setupCounter(10);
+console.log(counter2()); // 10
 ```
\ No newline at end of file