DRY & KISS Principles

What aspect of this form validation implementation violates the DRY principle?

const validateLoginForm = (values) => {
  const errors = {};
  
  if (!values.email) {
    errors.email = 'Required';
  } else if (!/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}$/i.test(values.email)) {
    errors.email = 'Invalid email address';
  }
  
  if (!values.password) {
    errors.password = 'Required';
  } else if (values.password.length < 8) {
    errors.password = 'Must be at least 8 characters';
  }
  
  return errors;
};

const validateRegistrationForm = (values) => {
  const errors = {};
  
  if (!values.email) {
    errors.email = 'Required';
  } else if (!/^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}$/i.test(values.email)) {
    errors.email = 'Invalid email address';
  }
  
  if (!values.password) {
    errors.password = 'Required';
  } else if (values.password.length < 8) {
    errors.password = 'Must be at least 8 characters';
  }
  
  if (!values.confirmPassword) {
    errors.confirmPassword = 'Required';
  } else if (values.confirmPassword !== values.password) {
    errors.confirmPassword = 'Passwords must match';
  }
  
  return errors;
};

The validation messages are hardcoded
The function names are too similar
The validation rules are duplicated
This code violates DRY by duplicating validation rules for email and password fields. A better approach would be to extract common validation rules: const validations = { email: { required: true, pattern: /^[A-Z0-9._%+-]+@[A-Z0-9.-]+\.[A-Z]{2,}$/i, message: 'Invalid email address' }, password: { required: true, minLength: 8, message: 'Must be at least 8 characters' } }; const validateField = (name, value, rules) => { if (rules.required && !value) return 'Required'; if (rules.pattern && !rules.pattern.test(value)) return rules.message; if (rules.minLength && value.length < rules.minLength) return rules.message; return null; }; const createValidator = (fields) => (values) => { const errors = {}; Object.keys(fields).forEach(field => { const error = validateField(field, values[field], validations[field]); if (error) errors[field] = error; }); return errors; }; const validateLoginForm = createValidator(['email', 'password']); const validateRegistrationForm = (values) => { const errors = validateLoginForm(values); if (!values.confirmPassword) { errors.confirmPassword = 'Required'; } else if (values.confirmPassword !== values.password) { errors.confirmPassword = 'Passwords must match'; } return errors; };
The error object structure is repeated

Next Question (17/20)