From Handling in React

App.js

import React,{Component} from 'react'
class App extends Component{
  constructor(){
    super()
    this.state = {
      firstName : "",
      lastName  :"",
      isFriendly:false,
      defaultText:"This is textArea"
    }
    this.handleChange = this.handleChange.bind(this)
  }
  handleChange(event){
    const {name,value,type,checked} = event.target
    type === "checkbox" ? this.setState({[name]:checked}) : this.setState({[name]:value})
  }
  render(){
    return (
      <form>
        <input type="text"
               value = {this.state.firstName}
               name = "firstName"
               placeholder = "First Name"
               onChange = {this.handleChange}
        />
        <br/>
        <input type="text"
               value = {this.state.lastName}
               name = "lastName"
               placeholder = "Last Name"
               onChange = {this.handleChange}
        />
        <textarea value={"Some default value"}
                 onChange ={this.handleChange}
        />
        <br/>
        <label>
        <input type = "checkbox"
               name = "isFriendly"
               checked = {this.state.isFriendly}
               onChange = {this.handleChange}
          /> Is Friendly
        </label>
        
      </form>
    )
  }
}
export default App