updated_change_handler_form_is_valid.js

  changeHandler = event => {
      const name = event.target.name;
      const value = event.target.value;

      const updatedControls = {
        ...this.state.formControls
      };
      const updatedFormElement = {
        ...updatedControls[name]
      };
      updatedFormElement.value = value;
      updatedFormElement.touched = true;
      updatedFormElement.valid = validate(value, updatedFormElement.validationRules);

      updatedControls[name] = updatedFormElement;

      let formIsValid = true;
      for (let inputIdentifier in updatedControls) {
        formIsValid = updatedControls[inputIdentifier].valid && formIsValid;
      }
    
      this.setState({
        formControls: updatedControls,
        formIsValid: formIsValid
      });
  }