From dea6850e85993e4e66c4878a048d438f558f8b60 Mon Sep 17 00:00:00 2001
From: Marcello Lamonaca <marcello.lamonaca@gmail.com>
Date: Fri, 19 Mar 2021 10:41:08 +0100
Subject: [PATCH] Add details to useEffect and class components

---
 JavaScript/React/React.md | 13 ++++++++-----
 1 file changed, 8 insertions(+), 5 deletions(-)

diff --git a/JavaScript/React/React.md b/JavaScript/React/React.md
index eeae63c..459f68f 100644
--- a/JavaScript/React/React.md
+++ b/JavaScript/React/React.md
@@ -114,6 +114,8 @@ class Button extends React.Component {
         super(props);
         this.state = {count: 0};
     }
+
+    componentDidMount() {}  // called on successful component mount
     
     handleClick = () => {
         this.setState({ count: this.state.count + 1 });
@@ -223,14 +225,15 @@ const [state, setState] = useState(default);
 
 ### `useEffect`
 
-Hook used to trigger an action on each reder of the component.
+Hook used to trigger an action on each reder of the component or when one of the watched items changes.
 
 ```js
-useEffect(() =>
-    // introduce side effect of the render
 
-    return () => {/* clean up side effect */}
-);
+useEffect(() => {
+    // "side effects" operations
+
+    return () => {/* clean up side effect */}  // optional
+}, [/* list of watched items, empty triggers once */]);
 ```
 
 ### Custom Hooks