EX_oop.js

class Validator {
    static REQUIRED = 'REQUIRED';
    static MIN_LENGTH = 'MIN_LENGTH';
  
    static validate(value, flag, validatorValue) {
      if (flag === this.REQUIRED) {
        return value.trim().length > 0;
      }
      if (flag === this.MIN_LENGTH) {
        return value.trim().length > validatorValue;
      }
    }
  }
  
  class User {
    constructor(uName, uPassword) {
      this.userName = uName;
      this.password = uPassword;
    }
  
    greet() {
      console.log('Hi, I am ' + this.userName);
    }
  }
  
  class UserInputForm {
    constructor() {
      this.form = document.getElementById('user-input');
      this.userNameInput = document.getElementById('username');
      this.passwordInput = document.getElementById('password');
  
      this.form.addEventListener('submit', this.signupHandler.bind(this));
    }
  
    signupHandler(event) {
      event.preventDefault();
      const enteredUserName = this.userNameInput.value;
      const enteredPassword = this.passwordInput.value;
  
      if (
        !Validator.validate(enteredUserName, Validator.REQUIRED) ||
        !Validator.validate(enteredPassword, Validator.MIN_LENGTH, 5)
      ) {
        alert(
          'Invalid input - username or password is wrong (password should be at least six characters).'
        );
        return;
      }
  
      const newUser = new User(enteredUserName, enteredPassword);
      console.log(newUser);
      newUser.greet();
    }
  }
  
  new UserInputForm();