reactjs useState() hook
import React, { useState } from 'react';
function Example() {
// Declare a new state variable, which we'll call "count"
const [count, setCount] = useState(0);
return (
<div>
<p>You clicked {count} times</p>
<button onClick={() => setCount(count + 1)}>
Click me
</button>
</div>
);
}useState hook example
function LoginForm() {
const [form, setState] = useState({
username: '',
password: ''
});
const printValues = e => {
e.preventDefault();
console.log(form.username, form.password);
};
const updateField = e => {
setState({
...form,
[e.target.name]: e.target.value
});
};
return (
<form onSubmit={printValues}>
<label>
Username:
<input
value={form.username}
name="username"
onChange={updateField}
/>
</label>
<br />
<label>
Password:
<input
value={form.password}
name="password"
type="password"
onChange={updateField}
/>
</label>
<br />
<button>Submit</button>
</form>
);
}usestate in react
const [x, setx] = useState(0);How to usestate in react
...
const [count, setCounter] = useState(0);
const [moreStuff, setMoreStuff] = useState(...);
...
const setCount = () => {
setCounter(count + 1);
setMoreStuff(...);
...
};usestate in react
The initial value will be assigned only on the initial render (if it’s a function, it will be executed only on the initial render).react usestate nedir
import { useState, useEffect } from 'react';
function ArkadasDurumu(props) {
const [onlineMi, onlineDurumuAta] = useState(null);
function handleDurumuDegistir(durum) {
onlineDurumuAta(durum.onlineMi);
}
useEffect(() => {
ChatAPI.arkadasDurumunaAboneOl(props.arkadas.id, handleDurumuDegistir);
return () => {
ChatAPI.arkadasDurumuAboneligindenCik(props.arkadas.id, handleDurumuDegistir);
};
});
if (onlineMi === null) {
return 'Yükleniyor...';
}
return onlineMi ? 'Online' : 'Offline';
}Copyright © 2021 Codeinu
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