Select with multiple="true" in react

select.js

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

class Select extends Component{
    constructor() {
        super();

        this.state = {
            folders: ['option 0', 'option 1', 'option 3', 'option 4'],
            values: []
        }
    }

    handleChange = (e) => {
        let options = e.target.options;
        let selectedOptions = [];

        for(let i = 0; i < options.length; i++) {
            if( options[i].selected ) {
                selectedOptions.push(options[i].value);
            }
        }

        this.setState({values: selectedOptions});
    }
 
    handleSubmit = (e) => {
        e.preventDefault();
        console.log(this.state.values);
    }
  
    render() {
        return (
            <form onSubmit={this.handleSubmit}>
                <select multiple="true" value={this.state.values} onChange={this.handleChange}>
                    {this.state.folders.map((item, index) => 
                        <option value={index} key={index}>{item}</option>    
                    )}
                </select>
                <button type="submit">Go</button>
            </form>
        );
    }
} 

ReactDOM.render(
    <Select />,
    document.getElementById('root')
);

example: http://jsfiddle.net/x5hz7qz5/