form state management with controlled components and partial application

example-form.js

import { partial } from '_';
import API from './API';

export default React.createClass({
  getInitialState() {
    return {
      username: '',
      password: '',
    };
  },
  
  handleChange(fieldName, {target: {value}}) {
    this.setState({[fieldName]: value});
  },
  
  handleSave(evt) {
    evt.preventDefault();
    API.login(this.state);
  },
  
  render() {
    return (
      <form onSubmit={this.handleSave}>
        <input
          onChange={partial(this.handleChange, 'username')}
          placeholder="Username"
          value={this.state.username}
        />
        <input
          onChange={partial(this.handleChange, 'password')}
          placeholder="Password"
          type="password"
          value={this.state.password}
        />
        <button type="submit">
          Login
        </button>
      </form>
    );
  },
})