修改hello，测试了useEffect的生命周期

.eslintcache

@@ -1 +1 @@
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src/App.tsx

@@ -1,27 +1,12 @@
-import React, { useState } from 'react';
+import React from 'react';
 import './App.css';
-import LikeButton from './components/LikeButton';
-import MouseTracker from './components/MouseTracker';
-import useMousePosition from './hooks/useMousePosition';
-import useURLLoader from './hooks/useURLLoader';
+import Hello from './components/Hello';
 
-interface IShowResult {
-  message: string;
-  status: string;
-}
 
 const App: React.FC = () => {
-  const [show, setShow] = useState(true);
-  const position = useMousePosition();
-  const [data, loading] = useURLLoader("https://dog.ceo/api/breeds/image/random",[show]);
-  const dogResult = data as IShowResult;
   return (
     <div className="App">
-      <LikeButton />
-      {show && <MouseTracker />}
-      <p><button onClick={() => { setShow(!show) }}>toogle</button></p>
-      <p>X: {position.x}, Y: {position.y}</p>
-      <p>{loading ? `小狗读取中` : <img src={dogResult && dogResult.message} />}</p>
+      <Hello message="sasa" />
     </div>
   );
 }

src/components/Hello.tsx

@@ -1,12 +1,31 @@
+import React, { useEffect, useState } from 'react';
 
-import React from 'react';
 
 interface IHelloProps {
-    message: string
+    message: string;
 }
 
-const Hello: React.FC<IHelloProps> = (props) =>{
-    return <h2>{props.message}</h2>
+const Hello: React.FC<IHelloProps> = (props) => {
+    const [data, setData] = useState(1);
+
+    useEffect(() => {
+        console.log("use effect - " + data);
+    }, []);
+
+    useEffect(() => {
+        console.log("use effect2 - " + data);
+    });
+
+    function click() {
+        const d: any = data + 1;
+        setData(d);
+    }
+    return (
+        <>
+            <h2>{props.message} {data}</h2>
+            <button onClick={click}> button </button>
+        </>
+    )
 }
 
 export default Hello;

src/components/LikeButton.tsx

@@ -3,7 +3,7 @@ import React, { useState, useEffect, useRef } from 'react';
 const LikeButton: React.FC = () => {
     //obj是存储容器，setObj是设置容器的函数名
     const [obj, setObj] = useState({ like: 0, on: true });
-    //使用useRef,在所有的render中数据都保持一直
+    //使用useRef,在所有的render中数据都保持一直，修改这个变量也不会引起组件从新render
     const likeRef = useRef(0);
 
     //这个useeffect没渲染完都会执行