Showing the count of checked checkboxes using vanilla javascript

Im currently working on a website that generates a random password. One part of it shows the safety of the current password. Until now i was only able to make the safety-indicator dependent on the current length of the password. I want to also include the current count of checked checkboxes in the safety indicator.

I tried this function to update the the count of checked checkboxes with "onchange":

function updateSafetyIndicator() {

    const checks = document.querySelector(".checks");
    const checkedCount = 0;

    for (var i = 0; i < checks.length; i++) {
        if (checks[i].checked) {
            checkedCount++;
        }
    }

    console.log(checkedCount)

    if (checkedCount <= 1) {
        passwordSafetyIndicator.id = "veryweak";
    }

    else if (checkedCount <= 2) {
        passwordSafetyIndicator.id = "weak";
    }

    else if (checkedCount <= 3) {
        passwordSafetyIndicator.id = "medium";
    }

    else if (checkedCount <= 4) {
        passwordSafetyIndicator.id = "strong";
    }
}