JSFiddle - React, Tailwind, and code Playground

HTML

<button id="btnDept">select Depts</button>
<div id="dialog" title="Select the Depts you want to include in the report" style="display:none;">
    <div>
        <section class="breakAfter">
            <label for="ckbxSelectAll">Select All</label>
            <input type="checkbox" id="ckbxSelectAll" />
            <label for="ckbxDeselectAll">Deselect All</label>
            <input type="checkbox" id="ckbxDeselectAll" />
        </section>
        <label for="ckbx2">2</label>
        <input type="checkbox" id="ckbx2" />
        <label for="ckbx3" id="lbl3">3</label>
        <input type="checkbox" id="ckbx3" />
    </div>
</div>

CSS

.breakAfter {
    display:block;
}

JavaScript

var deptsSelected = '';
$("#btnDept").click(function () {
    $("#dialog").dialog({
        modal: true
    });
    $("input:checkbox").click(function () {
        var checkedVal = $("label[for='" + this.id + "']").text();

        if (checkedVal == "Select All") {
            $(":checkbox").prop("checked", true);
            $("#ckbxDeselectAll").prop("checked", false);
            csv_val = $.map($(':checkbox:not(#' + this.id + '):checked'), function(elem, index) {
                return $("label[for='" + elem.id + "']").text();
            }).join(',');
            console.log(csv_val);
            // How can I add all of the vals to deptsSelected (except "Select All" and "Deselect All")? 
        } else if (checkedVal == "Deselect All") {
            $(":checkbox").prop("checked", false);
            $("#ckbxDeselectAll").prop("checked", true);
            deptsSelected = '';
        } else {
            if (deptsSelected.indexOf(checkedVal) < 0) {
                deptsSelected += $("label[for='" + this.id + "']").text() + ',';
            }
        }
        alert(deptsSelected);
    });
});