blog-rhf-basic_react_form.js

class MyFrom extends Component {
  constructor(props) {
    super(props);
    this.state = {phoneNumber: ''};

    this.handleChangePhoneNumber = this.handleChangePhoneNumber.bind(this);
    this.handleSubmit = this.handleSubmit.bind(this);
  }

  handleChangePhoneNumber(event) {
    this.setState({value: event.target.value});
  }

  handleSubmit(event) {
    alert('Hi your phone Number is: ' + this.state.value);
    event.preventDefault();
  }

  render() {
    return (
      <form onSubmit={this.handleSubmit}>
        <label>
          Phone Number:
          <input type="text" value={this.state.value} onChange={this.handleChangePhoneNumber} />
        </label>
        <input type="submit" value="Submit" />
      </form>
    );
  }
}

this.setState({phoneNumber: event.target.value});
value={this.state.phoneNumber}

Hi, there is a typo in the class name MyFrom > MyForm