?$row.find("[id$='_cb']:checked").val()
""
?$row.find("[id$='_cb']:checked")[0].checked
true
?$row.find("[id$='_cb']:checked")[0]
{object}
    accept: ""
    accessKey: ""
    align: ""
    all: {Count = 0}
    alt: ""
    attributes: {Count = 108}
    behaviorUrns: {...}
    border: ""
    canHaveChildren: false
    canHaveHTML: false
    checked: true
    childNodes: {Count = 0}
    children: {Count = 0}
    className: ""
    clientHeight: 20
    clientLeft: 0
    clientTop: 0
    clientWidth: 20
    complete: false
    contentEditable: "inherit"
    currentStyle: {...}
    dataFld: ""
    dataFormatAs: ""
    dataSrc: ""
    defaultChecked: true
    defaultValue: ""
    dir: ""
    disabled: false
    document: {object}
    dynsrc: ""
    filters: {...}
    firstChild: null
    form: {Count = 18}
    height: 72286252
    hideFocus: false
    hspace: 0
    id: "ctlGrid_ctl04_cb"
    indeterminate: false
    innerHTML: ""
    innerText: ""
    isContentEditable: false
    isDisabled: false
    isMultiLine: false
    isTextEdit: false
    lang: ""
    language: ""
    lastChild: null
    loop: 1
    lowsrc: ""
    maxLength: 2147483647
    name: "ctlGrid$ctl04$cb"
    nextSibling: {object}
    nodeName: "INPUT"
    nodeType: 1
    nodeValue: null
    offsetHeight: 20
    offsetLeft: 223
    offsetParent: {object}
    offsetTop: 4
    offsetWidth: 20
    outerHTML: "<INPUT id=ctlGrid_ctl04_cb type=checkbox CHECKED value="" name=ctlGrid$ctl04$cb>"
    outerText: ""
    ownerDocument: {object}
    parentElement: {object}
    parentNode: {object}
    parentTextEdit: {object}
    previousSibling: { }
    readOnly: false
    readyState: "complete"
    recordNumber: null
    runtimeStyle: {object}
    scopeName: "HTML"
    scrollHeight: 20
    scrollLeft: 0
    scrollTop: 0
    scrollWidth: 20
    size: 20
    sourceIndex: 50
    src: ""
    Start: "fileopen"
    status: true
    style: {object}
    tabIndex: 0
    tagName: "INPUT"
    tagUrn: ""
    title: ""
    type: "checkbox"
    uniqueID: "ms__id1"
    uniqueNumber: 1
    useMap: ""
    value: ""
    vrml: ""
    vspace: 0
    width: 0