<div id="root"></div>

div{
  text-align:center
}

class UserInput extends React.Component{

  state = {
      name:"reactgo"
  }

  handleChange = (e) =>{
    this.setState({
        name: e.target.value
    })
  }

   render(){
    return(
     <div>
      <h1>{this.state.name}</h1>
      <input type="text" onChange={this.handleChange} value={this.state.name} />
     </div>
    )
   }

}

ReactDOM.render(<UserInput/>,document.querySelector('#root'))