OnChange event using React JS for drop down

Question

var MySelect = React.createClass({
     change: function(){
         return document.querySelector('#lang').value;
     },
     render: function(){
        return(
           <div>
               <select id="lang">
                  <option value="select" onChange={this.change}>Select</option>
                  <option value="Java" onChange={this.change}>Java</option>
                  <option value="C++" onChange={this.change}>C++</option>
               </select>
               <p></p>
               <p value={this.change}></p>
           </div>
        );
     }
});

React.render(<MySelect />, document.body);

The onChange event does not work.

Felix Kling · Accepted Answer · 2015-03-05T01:19:07.313

The change event is triggered on the <select> element, not the <option> element. However, that's not the only problem. The way you defined the change function won't cause a rerender of the component. It seems like you might not have fully grasped the concept of React yet, so maybe "Thinking in React" helps.

You have to store the selected value as state and update the state when the value changes. Updating the state will trigger a rerender of the component.

var MySelect = React.createClass({
     getInitialState: function() {
         return {
             value: 'select'
         }
     },
     change: function(event){
         this.setState({value: event.target.value});
     },
     render: function(){
        return(
           <div>
               <select id="lang" onChange={this.change} value={this.state.value}>
                  <option value="select">Select</option>
                  <option value="Java">Java</option>
                  <option value="C++">C++</option>
               </select>
               <p></p>
               <p>{this.state.value}</p>
           </div>
        );
     }
});

React.render(<MySelect />, document.body);

Also note that <p> elements don't have a value attribute. React/JSX simply replicates the well-known HTML syntax, it doesn't introduce custom attributes (with the exception of key and ref). If you want the selected value to be the content of the <p> element then simply put inside of it, like you would do with any static content.

Learn more about event handling, state and form controls:

how can i get the inner text without the `value` being the same as the inner text? — blankface, Apr 23 '18 at 06:20
@FelixKling when I use textContent it print all the options inside de Select tag. What can I do to get only the selected ? — Juan, Jun 30 '20 at 19:00
@FelixKin: use event.persist() in onChange function as target will be null if this is not used. — Amrutha VS, Oct 21 '20 at 05:06

score 88 · Answer 2 · edited Oct 22 '20 at 20:23

88

React Hooks (16.8+):

const Dropdown = ({
  options
}) => {
  const [selectedOption, setSelectedOption] = useState(options[0].value);
  return (
      <select
        value={selectedOption}
        onChange={e => setSelectedOption(e.target.value)}>
        {options.map(o => (
          <option key={o.value} value={o.value}>{o.label}</option>
        ))}
      </select>
  );
};

edited Oct 22 '20 at 20:23

Malcolm Crum

4,345
4
30
49

answered Jul 18 '19 at 09:28

Austin Gayler

4,038
8
37
60

Kirk Strobeck · Answer 3 · 2018-05-10T00:28:52.000

import React, { PureComponent, Fragment } from 'react';
import ReactDOM from 'react-dom';

class Select extends PureComponent {
  state = {
    options: [
      {
        name: 'Select…',
        value: null,
      },
      {
        name: 'A',
        value: 'a',
      },
      {
        name: 'B',
        value: 'b',
      },
      {
        name: 'C',
        value: 'c',
      },
    ],
    value: '?',
  };

  handleChange = (event) => {
    this.setState({ value: event.target.value });
  };

  render() {
    const { options, value } = this.state;

    return (
      <Fragment>
        <select onChange={this.handleChange} value={value}>
          {options.map(item => (
            <option key={item.value} value={item.value}>
              {item.name}
            </option>
          ))}
        </select>
        <h1>Favorite letter: {value}</h1>
      </Fragment>
    );
  }
}

ReactDOM.render(<Select />, window.document.body);

very good. and you can see the result of change with this way

{this.state.value} — Mohammad Farahani, Jul 15 '18 at 06:29

score 10 · Answer 4 · answered Apr 22 '21 at 19:43

  handleChange(value, selectOptionSetter) => {
     selectOptionSetter(value)
     // handle other stuff like persisting to store etc
   }

  const Dropdown = (props) => {
  const { options } = props;
  const [selectedOption, setSelectedOption] = useState(options[0].value);
  return (
      <select
        value={selectedOption}
        onChange={e => handleChange(e.target.value, setSelectedOption)}>
        {options.map(o => (
          <option key={o.value} value={o.value}>{o.label}</option>
        ))}
      </select>
  );
};

score 4 · Answer 5 · answered Apr 15 '20 at 05:31

If you are using select as inline to other component, then you can also use like given below.

<select onChange={(val) => this.handlePeriodChange(val.target.value)} className="btn btn-sm btn-outline-secondary dropdown-toggle">
    <option value="TODAY">Today</option>
    <option value="THIS_WEEK" >This Week</option>
    <option value="THIS_MONTH">This Month</option>
    <option value="THIS_YEAR">This Year</option>
    <option selected value="LAST_AVAILABLE_DAY">Last Availabe NAV Day</option>
</select>

And on the component where select is used, define the function to handle onChange like below:

handlePeriodChange(selVal) {
    this.props.handlePeriodChange(selVal);
}

score 4 · Answer 6 · edited Nov 09 '21 at 07:06

4

I'll add this here, in case it helps someone because this was the solution that helped me.

This is to get the SELECTED INDEX. Not for the value. (Worked for me because my options list was a list of numbers)

const [selectedOption, setSelectedOption] = useState(0)
<select onChange={event => setSelectedOption(event.target.options.selectedIndex)}>

edited Nov 09 '21 at 07:06

Dharman

30,962
25
85
135

answered Nov 09 '21 at 07:00

PWJ

83
10

score 3 · Answer 7 · answered Feb 25 '23 at 12:01

Now you can use it like this

import { useState } from 'react';
import './App.css';

function App() {
  const [selectedItem, setSelectedItem] = useState("Counter")
  const handleChange = (e) => {
    setSelectedItem(e.target.value)
  }
  return (
    <div className="App">
      <p>You have selected {selectedItem}</p>
      <select name='item-selected' value={selectedItem} onChange={handleChange}>
        <option value="Counter">Counter</option>
        <option value="useEffect">useEffect</option>
      </select>
    </div>
  );
}

export default App;

score 1 · Answer 8 · answered Apr 04 '19 at 14:12

Thank you Felix Kling, but his answer need a little change:

var MySelect = React.createClass({
 getInitialState: function() {
     return {
         value: 'select'
     }
 },
 change: function(event){
     this.setState({value: event.target.value});
 },
 render: function(){
    return(
       <div>
           <select id="lang" onChange={this.change.bind(this)} value={this.state.value}>
              <option value="select">Select</option>
              <option value="Java">Java</option>
              <option value="C++">C++</option>
           </select>
           <p></p>
           <p>{this.state.value}</p>
       </div>
    );
 }
});
React.render(<MySelect />, document.body);

Why are you adding `this.change.bind` in `onChange`? – Junior Usca Jul 11 '19 at 15:05 — Junior Usca, Jul 11 '19 at 15:05

score 0 · Answer 9 · answered Jun 26 '20 at 18:32

var MySelect = React.createClass({
getInitialState: function() {

var MySelect = React.createClass({
 getInitialState: function() {
     return {
         value: 'select'
     }
 },
 change: function(event){
     event.persist(); //THE MAIN LINE THAT WILL SET THE VALUE
     this.setState({value: event.target.value});
 },
 render: function(){
    return(
       <div>
           <select id="lang" onChange={this.change.bind(this)} value={this.state.value}>
              <option value="select">Select</option>
              <option value="Java">Java</option>
              <option value="C++">C++</option>
           </select>
           <p></p>
           <p>{this.state.value}</p>
       </div>
    );
 }
});
React.render(<MySelect />, document.body);

<script src="https://cdnjs.cloudflare.com/ajax/libs/react/16.6.3/umd/react.production.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/react-dom/16.6.3/umd/react-dom.production.min.js"></script>

OnChange event using React JS for drop down

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