JSFiddle - React, Tailwind, and code Playground

JavaScript

// will store list of rules
var rules = []

// at least one capital letter rule
rules.one_capital_letter = {
	fail_message: 'password needs at least one capital letter',
  validate: function(password){
    return /[A-Z]/.test(password)
  }
}

// at least six letters rule
rules.at_least_six_letters = {
	fail_message: 'password needs to have at least 6 characters',
  validate: function(password){
    return password.length >= 6
  }
}

function validate_password(password) {

	// goes through all the rules
	for(rule in rules) {
  	if(!rules[rule].validate(password)) {
      return {success: false, message: rules[rule].fail_message}
    }
  }
  
  // return success after all rules are checked
  return {success: true, message: 'password validated successfully'}
}

// Test if it works
var test_strings = ['abcd', 'Abcd', 'Abcdef']
for(i in test_strings) {
	$('body').append(test_strings[i] + ': ' + validate_password(test_strings[i]).message + '<br>')
}