useeffect react
useEffect(() => {
return () => {
console.log("cleaned up");
};
}, []);function App() {
const [count, setCount] = useState(0);
useEffect(() => {
longResolve().then(() => {
alert(count);
});
}, []);
return (
<div>
<button
onClick={() => {
setCount(count + 1);
}}
>
Count: {count}
</button>
</div>
);
} useEffect(() => {
},[]);import React, { useState, useEffect } from 'react';
function Example() {
const [count, setCount] = useState(0);
// Similar to componentDidMount and componentDidUpdate:
useEffect(() => {
// Update the document title using the browser API
document.title = `You clicked ${count} times`;
});
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}useEffect(() => {
// code goes here
return () => {
// cleanup code codes here
};
},[]);useEffect(() => {
window.addEventListener('mousemove', () => {});
// returned function will be called on component unmount
return () => {
window.removeEventListener('mousemove', () => {})
}
}, [])