function App (){
const [count, setCount] = React.useState(0);
const [myName, setMyName] = React.useState('Ray');
function sayHi () {
window.alert('Hello Ray.');
}
React.useEffect(() => {
console.log('render');
}, [ count ])
return (
<div>
<button type="button" onClick={() => setCount(count + 1)}>
Count is: { count }
</button>
<hr />
<button type="button" onClick={() => setMyName('QQ')}>
改名字 { myName }
</button>
</div>
)
}
const app = document.querySelector('#app');
const root = ReactDOM.createRoot(app);
root.render(<App />);
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