foo.jsx

class Foo extends Component {
  state = {
    email: '',
    password: '',
  };
  
  handleChange = e => {
    this.setState({
      [e.target.name]: e.target.value,
    });
  };

render() {
    return (
      <input name="email" value={this.state.email} onChange={handleChange} />
      <input name="password" value={this.state.password} onChange={handleChange} />
    );
  } 
}