formatting map array

hi all

<input id="grndsrc" type="checkbox" name="advsrc" checked /><input id="fnamesrc" type="checkbox" name="advsrc" /><input id="lnamesrc" type="checkbox" name="advsrc" /><input id="dobsrc" type="checkbox" name="advsrc" /><input id="telsrc" type="checkbox" name="advsrc" /><input id="ssnsrc" type="checkbox" name="advsrc" />

this current code maps the above checkbox group

function detectsrc() {
                var checked = $(":checkbox[name='advsrc']").map(function (idx, ele) {
                    return (ele.checked) ? { id: this.id, val: $('#RegSrc' + 'srcctl').val() } : { id: this.id, val: '' };
                }).get();
                return (JSON.stringify(checked));
}

output is 

[{"id":"grndsrc","val":"a"},{"id":"fnamesrc","val":"null"},{"id":"lnamesrc","val":"null"},{"id":"dobsrc","val":"null"},{"id":"telsrc","val":"null"},{"id":"ssnsrc","val":"null"}]

I want the output looks like this

{"grndsrc":"a","fnamesrc":"","lnamesrc":"","dobsrc":"","telsrc":"","ssnsrc":""}