jQuery - Getting values of text input and checkboxes into one string (or array)

I have three types of items I'm trying to get into a comma-separated string (or array), which I want to display and use to form a URL later. How can I get these three types of data into the same string or array?

1. An existing POST string
2. Free input from a text field with an Add button
3. The values of a series of checkbokes

Here's the fiddle.

I'm using this HTML:

<div class="srs-display">existingPostString</div>

<ul id="srs" class="srs">
    <!-- START TEXT INPUT FIELD -->
    <li class="sr">
        <div class="masonry-well">
            <input id="sr-custom" type="text" placeholder="Add your own">
            <a class="add-sr-custom">Add</a>
        </div>
    </li>
    <!-- END TEXT INPUT FIELD -->
    <!-- START CHECKBOXES -->
    <li class="sr">
        <div class="masonry-well">
            <input id="srPredefined1" type="checkbox" name="srPredefined1" value="srPredefined1">
            <label for="srPredefined1" class="ts-helper">srPredefined1</label>
        </div>
    </li>
    <li class="sr masonry-item">
        <div class="masonry-well">
            <input id="srPredefined2" type="checkbox" name="srPredefined2" value="srPredefined2">
            <label for="srPredefined2" class="ts-helper">srPredefined2</label>
        </div>
    </li>
    <li class="sr masonry-item">
        <div class="masonry-well">
            <input id="srPredefined3" type="checkbox" name="srPredefined3" value="srPredefined3">
            <label for="srPredefined3" class="ts-helper">srPredefined3</label>
        </div>
    </li>
    <!-- END CHECKBOXES -->
</ul>

And here's the JS I tried so far:

$('input[type="checkbox"]').bind('change', function() {
    var srs = 'existingPostString';

    $('input[type="checkbox"]').each(function(index, value) {
        if (this.checked) {
            /*add*/ /*get label text associated with checkbox*/
            srs += ($(this).val() + ', ');
        }
    });
    if (srs.length > 0) {
        srs = srs.substring(0,srs.length-2);
    } else {
        srs = 'No checks';
    }

    $('.srs-display').html(srs);
});

$(".add-sr-custom").on('click', function() {
    var srs = 'existingPostString';

    srs +=  ',' + $('#sr-custom').val();
    $('.srs-display').text(srs);
})