Login.jsx

class Login extends Component {
  constructor() {
    super();
    
    this.changeField = this.changeField.bind(this);
    this.login = this.login.bind(this);
    this.state = {
      login: ``,
      password: ``,
    };
  }
  
  changeField(field) {
    return (event) => {
      this.setState({ [field]: event.target.value });
    };
  }
  
  login() {
    const { login, password } = this.state;
    myAjaxCall({ login, password });
  }
  
  render() {
    return (
      <form>
        <input type="text" onChange={changeField("login")} value={this.state.login} />
        <input type="password" onChange={changeField("password")} value={this.state.password} />
        <button type="button" onClick={this.login} />
      </form>
    );
  }
}