Jquery .map().join(" , ") text is not joining the comma (,)
<p>I'm using <code>label</code> and hidden input <code>checkbox</code> and on <code>.change</code> of checkbox. I'm getting the label text by Jquery <code>.map()</code> and want to <code>.join(",")</code> text with <code>,</code>.</p>

<p>Text is coming and everything is working fine but the comma (,) is not coming anyhow.</p>

<blockquote>
  <p>I'm getting result <strong><em>Checkbox 1Checkbox 2Checkbox 5</em></strong> and I want <strong><em>Checkbox 1, Checkbox 2, Checkbox 5</em></strong> </p>
</blockquote>

<p><a href="https://jsfiddle.net/usx8Lkc5/6/" rel="noreferrer"><strong>find fiddle demo</strong></a></p>

<p>Highlight Code:</p>

<pre><code>$(".combo").append( $(txt).map(function() {
    return $(this).text();
}).get().join( " ," ) );
</code></pre>

<p>Code:</p>

<pre><code>var checked = [];
$('input[type="checkbox"]').change(function(e) {
    var num_checked = $('input[type="checkbox"]:checked').length;

    if (num_checked &gt; 3) {
        checked[checked.length - 1].prop('checked', false);
        if(checked[checked.length - 1].prop('checked', false)){
            checked[checked.length - 1].parents('label').removeClass("active");
            var et = checked[checked.length - 1].parents('label').text();
            $('.combo').text(function () {
                return $(this).text().replace(et, '');  
            });

        }
        checked.pop();
    }
    if($.inArray($(this), checked) &lt; 0){
        checked.push($(this));
        if($(this).is(':checked')){
            $(this).parents('label').addClass("active");
            var txt = $(this).parents('label');
            $(".combo").append( $(txt).map(function() {
                return $(this).text();
            }).get().join( " ," ) );

        } else{
            $(this).parents('label').removeClass("active-cb");
            //$('.selectedSwitch').text('');
            var qr = $(this).parents('label').text();
            $('.combo').text(function () {
                return $(this).text().replace(qr, '');  
            });
        }
    }
});
</code></pre>