<input type="checkbox" id="1"/>
<label for="1">選項一</label>
<br/>
<input type="checkbox" id="2"/>
<label for="2">選項二</label>
<br />
<input type="checkbox" id="3"/>
<label for="3">選項三</label>
<br/>
<span id="result"></span>

$(function() {
    $("input[type=checkbox]").on("click", function () {
 var vIds = "";
 $("input:checked").each(function() {
     vIds += $(this).attr('id') + ",";
 });
 if (vIds.length > 0) {
     vIds = vIds.substring(0, vIds.length - 1);
 }
 $('#result').text(vIds);
    });
});