How to trim off last character in an Array - jQuery

so today I have an Array with several strings in them, all ending with , example: jazz, latin, trance,

I need to remove the , off the last element in the Array. Searching Stackoverflow I found several answers and tried the code below, but no luck so far :(

// How I'm generating my Array (from checked checkboxes in a Modal)
    role_Actor = [];
    $('.simplemodal-data input:checked').each(function() {
        role_Actor.push($(this).val());
    });

// roleArray = my Array

var lastEl = roleArray.pop();
    lastEl.substring(0, lastEl.length - 1);
    roleArray.push($.trim(lastEl));


// My function that displays my strings on the page
    $.each(roleArray, function(index, item) {
        $('.'+rowName+' p').append(item+', ');
    });


// Example of the Array:
    Adult Animated, Behind the Scenes, Documentary,

Thanks for taking a look!

---

Thanks @Claire Anthony! for the fix!!!

Answer

You forgot to assign lastEl before putting it back in to roleArray:

lastEl = lastEl.substring(0, lastEl.length - 1);

As the comments suggest, and as you're just using this for display purposes, you should remove the commas from the elements in roleArray and use the join method, like so:

var roleArray = ['latin', 'jazz', 'trance'];
$('#example').append(roleArray.join(', '));