Adding all option for list of options

add-all-option.js

$('document').ready(function () {

    // Below code takes care of adding All checkbox to options.
    var i = 0;
    $(".form-checkboxes").each(function () {
        i++;

        // Add events.all checkbox only if there are more than 2 options.
        if ($(this).children().length > 2) {

            // Adds the all checkbox
            addAllCheckbox($(this), 'All');

            // On click of All checkbox, check/uncheck all the options.
            $(".form-checkboxes .form-checkall").change(function () {
                // if All option is checked, check all the options.
                if ($(this).prop("checked") == true) {
                    checkboxController($(this), true);
                }

                // if All option is un-checked,un-check all the options.
                if ($(this).prop("checked") == false) {
                    checkboxController($(this), false);
                }
            });

            // Takes care of unchecking the All option, if any child option is unchecked.
            $(".form-checkboxes input:checkbox").change(function () {
                if ($(this).prop("checked") == false) {
                    $(this).parents('.form-checkboxes').find(".form-checkall").prop('checked', false);
                }
            });
        }
    });
        
    // Checks/unchecks all the options, depending on state passed to this function.
    function checkboxController(allCheckbox, state) {
        console.log(allCheckbox.parents('.form-checkboxes').find(".form-checkbox"));
        allCheckbox.parents('.form-checkboxes').find("input:checkbox").each(function () {
            $(this).prop('checked', state);
        });
    }

    // Adds the all checkbox to option group
    function addAllCheckbox(container, name) {
        var checkbox_all = "<div class='form-item js-form-item form-type-checkbox js-form-type-checkbox checkbox'>";
        checkbox_all += "<label for='checkbox-all' class='control-label option checkbox-all-label'>";
        checkbox_all += "<input type= 'checkbox' value='All' class='checkbox-all form-checkbox form-checkall'>";
        checkbox_all += name + "</label></div>";
        container.prepend(checkbox_all);
    }
}