reactjs-component.jsx

class Login extends React.Component {
 
  changeForm = ({ target }) => {
   this.setState({ [target.name]: target.value })
  }
  
  render() {
   const { firstName, lastName } = this.state
    
   return (
     <div>
       <input value={firstName} name="firstName" onChange={this.changeForm} />
       <input value={lastName} name="lastName" onChange={this.changeForm} />
     </div>
   )
  }
  
}