What is the differece between my codes when find checkbox in IE8?

I have tree type of checkbox which class is named checkAll,checkRow,checkCell in my grid.When I click checkAll checkbox ,all the checkbox will be checked.When I click the checkRow checkbox,the checkbox in this row will be checked. Now I use the same code to create checkAll,checkRow event,I find checkAll' event work well,but incheckRow` event it is wrong.It says Jscript error.And I try to change it use juqery way and it works well.What is the differece between my codes when find checkbox in IE8?

First way:checkAll works well,checkRow do not work

$("#checkAll").on("click", function (e) {
    var target = $(e.target), item, checked = target.prop("checked"),
    checkboxes = $("#Grid input");
    checkboxes.each(function (i, v) {
        item = $(v);
        if(!item.prop("disabled"))
            item.prop("checked", checked);
    });
});

$("#Grid").on("click", ".checkRow", function (e) {
    var target = $(e.target), checked = target.prop("checked"),
    td = target.parent("td"), tr = td.parent("tr"),
    checkboxes = tr.find("input[class!='checkRow']");
    checkboxes.each(function (i, v) {
        item = $(v); //in this row Jscript error,wrong property in IE8,but firfox work well
        item.prop("checked", checked);
    });
});

Second way in checkrow event and work well

$("#Grid").on("click", ".checkRow", function (e) {
    var target = $(e.target), checked = target.prop("checked"),
    td = target.parent("td"), tr = td.parent("tr"),
    checkboxes = tr.find("input[class!='checkRow']");
    checkboxes.prop("checked", checked);//work well
});