get an element's id

Yes you can just use the .id property of the dom element, for example:

myDOMElement.id

Or, something like this:

var inputs = document.getElementsByTagName("input");
for (var i = 0; i < inputs.length; i++) {
  alert(inputs[i].id);
}

Yes you can simply say:

function getID(oObject) 
{
    var id = oObject.id;
    alert("This object's ID attribute is set to \"" + id + "\"."); 
}

Check this out: ID Attribute | id Property

This would work too:

document.getElementsByTagName('p')[0].id

(If element where the 1st paragraph in your document)

Super Easy Way is

  $('.CheckBxMSG').each(function () {
            var ChkBxMsgId;
            ChkBxMsgId = $(this).attr('id');
            alert(ChkBxMsgId);
        });

Tell me if this helps