JAVASCRIPT

use onchange with react select

const [valueState,setValueState] = useState("")
// create a function that handle the React-select event and
// save the value of that event on an state every time the component change
    const handler = (event) => {
        const value = event.value
        setValueState(value)
    }
<Select options={"your options"} onChange={handler}/>

handlechange in react

const [data, setData] = useState({
    name: "",
  });
const handleData = (name, value) => {
    setData({
      ...data,
      [name]: value,
    });
  };
onChange={(e) => handleData("name", e.target.value)}

React onChange handler

return (
  <input 
    type="text"
    name="firstName"
    onChange={ (event) => setName(event.target.value) }  
    value={name} />
)

handle onchange react

import React, { Component } from 'react';

import './App.css';
import Header from './Header';

class App extends Component {

  constructor(props) {
    super(props);
   this.state = {name: "Michael"}

  }
   changeTitle = (e) =>{
      this.setState({name: e.target.value});
    }

  render() {
    return (
      <div className="App">
        <Header title={this.state.name}/>
        <p className="App-intro">
          Type here to change name.
        <input type="text" onChange={this.changeTitle}/>
        </p>
      </div>
    );
  }
}

export default App;

what does onchange do in react

In React, onChange is used to handle user input in real-time.

If you want to build a form in React, you need to use this event to track 
the value of input elements.

onChange in react js

import React from "react";

function App() {
  function handleChange(event) {
    console.log(event.target.value);
  }

  return (
    <input
      type="text"
      name="firstName"
      onChange={handleChange}
    />
  );
}

export default App;