Just a little Form w/ React and Controlled Components!

react-example-form-controlled-components.js

import React from 'react';

const SomeForm = React.createClass({
  getInitialState() {
    return {firstName: ''}
  },
  
  handleChangeFirstName(event) {
    this.setState({
      firstName: event.target.value
    });
  },
  
  handleSubmit(event) {
    event.preventDefault();
    alert(`First Name: ${this.state.firstName}!`);
  },
  
  render() {
    const {firstName} = this.state;
    const secretMessage = firstName.length > 0 ? `for ${firstName}` : '';
    
    return (
      <div>
        <h3>A Great Form {secretMessage}</h3>
        <form onSubmit={this.handleSubmit}>
          First Name <input 
            type="text"
            value={firstName}
            onChange={this.handleChangeFirstName}
          />
          <button>Submit</button>
        </form>
      </div>
    )
  }
});

ReactDOM.render(
  <SomeForm />,
  document.getElementById('app')
)

Codepen URL: http://codepen.io/erikthedeveloper/pen/PNyprZ?editors=1010