PHP $ _POST值返回'0'

Question

I have a javascript function that modifies a series of dropdown fields actively based on what's appended to another dropdown, so they're all linked.

function addOpt() {
    var opt = [ document.getElementById('party') , document.getElementById('bride') , document.getElementById('groom') , document.getElementById('moh') , document.getElementById('bestman') , document.getElementById('bst1') , document.getElementById('bst2') , document.getElementById('bst3') , document.getElementById('bst4') , document.getElementById('bst5') , document.getElementById('bst6') , document.getElementById('bst7') , document.getElementById('gst1') , document.getElementById('gst2') , document.getElementById('gst3') , document.getElementById('gst4') , document.getElementById('gst5') , document.getElementById('gst6') , document.getElementById('gst7') , document.getElementById('ringbearer') , document.getElementById('fg1') , document.getElementById('fg2') , document.getElementById('rd1') , document.getElementById('rd2') ];
    var addition = document.getElementById('addition').value.capitalize(true);
    var obj;
    var i;
    for (i = 0; i < opt.length; i++) {
        obj = document.createElement('option');
        obj.appendChild(document.createTextNode(addition));
        obj.value = addition;
        add = opt[i].appendChild(obj);
    }
}

The problem I have now is when I try to post these <select> fields to a form with method "post" all $_POST values return '0'. No data.

Here is the jsFiddle I'm not sure why the post values won't return.