example.js

// setState
import React from 'react'

class MyForm extends React.Component {
  constructor (props) {
    super(props)

    this.state = {
      email: '',
      password: '',
      submitting: false,
    }
  }

  render () {
    return (
      <form onSubmit={(e) => {
        e.preventDefault()
        // Do something with this.state
      }}>
        <input type='email' value={this.state.email} onChange={(e) => this.setState({ email: e.target.value})} />
        <input type='password' value={this.state.password} onChange={(e) => this.setState({ password: e.target.value})} />
        <button type='submit' disabled={this.state.submitting}>Login</button>
      </form>
    )
  }
}

// redux-form
import React from 'react'
import { reduxForm } from 'redux-form'

const MyForm = (props) => (
  <form onSubmit={this.props.handleSubmit(({email, password}) => {
    // Do something with email and password.
  })}>
    <input type='email' {...this.props.email} />
    <input type='password' {...this.props.password} />
    <button type='submit' disabled={this.props.submitting}>Login</button>
  </form>
)

const formConfig = {
  form: 'login',
  fields: ['email', 'password'],
}

export default reduxForm(formConfig)(MyForm)