script.js

function verify() {
    try {
        var password = document.forms['form']['password'].value;
        var userName = document.forms['form']['userName'].value;
        if (password == null || password == "" || userName == null || userName == "") {
            document.getElementById("error").innerHTML = "User name and password are required";
            return false;
        }

        var checkboxes = document.getElementsByName("authorities");
        var okay = false;
        var arr = [];
        for (var i = 0; i < checkboxes.length; i++) {
            if (checkboxes[i].checked) {
                okay = true;
                arr.push(checkboxes[i].value);
                // break;
            }
        }
        if (arr.length == 0) {
            document.getElementById("error").innerHTML = "You must select at least one role";
            okay = false;
        } else {
            okay = true;
        }

        var okay2 = true;
        if (arr.includes("ROLE_MANAGER") && !arr.includes("ROLE_USER")) {
            document.getElementById("error").innerHTML = "To add a manager role, you should ALSO check a user role";
            okay2 = false;
        } else {
            okay2 = true;
        }
        console.log('okay1: ' + okay + " okay2: " + okay2);
        return okay && okay2;

    } catch (err) {
        alert(err);
    }
}

document.addEventListener('DOMContentLoaded', function () {
    document.getElementById('ROLE_MANAGER').onclick = function () {
        var userCheckbox = document.getElementById('ROLE_USER');
        var managerCheckbox = document.getElementById('ROLE_MANAGER');

        if (!managerCheckbox.checked) {
            userCheckbox.checked = false;
        } else {
            userCheckbox.checked = true;
        }
    }
});