componentwillunmount in react hooks code example
Example 1: component unmount hooks
useEffect(() => {
window.addEventListener('mousemove', () => {});
return () => {
window.removeEventListener('mousemove', () => {})
}
}, [])
Example 2: useeffect with cleanup
useEffect(() => {
return () => {
};
},[]);
Example 3: useEffect
import React, { useState, useEffect } from 'react';
function Example() {
const [count, setCount] = useState(0);
useEffect(() => {
document.title = `You clicked ${count} times`;
});
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}
Example 4: componentwillunmount hooks
useEffect(() => {
window.addEventListener('mousemove', () => {});
return () => {
window.removeEventListener('mousemove', () => {})
}
}, [])
Example 5: component did update hooks
import React, { useState, useEffect } from 'react';
function Example() {
const [count, setCount] = useState(0);
useEffect(() => {
document.title = `You clicked ${count} times`;
},[count]);
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}
Example 6: useeffect componentdidmount
useEffect(() => {
messagesRef.on('child added', snapshot => {
const message = snapshot.val();
message.key = snapshot.key;
setMessages(messages.concat(message));
}, []);