How to check all Cheldren Nodes when parent node checked in Asp.net with C#

in C# we have to write

  trView.Attributes.Add("onclick", "OnCheckBoxCheckChanged(event)"); 


 

<script language="javascript" type="text/javascript">
        function OnCheckBoxCheckChanged(evt) {
           
            var src = window.event != window.undefined ? window.event.srcElement : evt.target;
            var isChkBoxClick = (src.tagName.toLowerCase() == "input" && src.type == "checkbox");
            if (isChkBoxClick) {
                var parentTable = GetParentByTagName("table", src);
                var nxtSibling = parentTable.nextSibling;
                if (nxtSibling && nxtSibling.nodeType == 1)//check if nxt sibling is not null & is an element node
                {
                    if (nxtSibling.tagName.toLowerCase() == "div") //if node has children
                    {
                        //check or uncheck children at all levels
                        CheckUncheckChildren(parentTable.nextSibling, src.checked);
                    }
                }
                //check or uncheck parents at all levels
               // CheckUncheckParents(src, src.checked); //commented not required any way
            }
        }
        function CheckUncheckChildren(childContainer, check) {
            var childChkBoxes = childContainer.getElementsByTagName("input");
            var childChkBoxCount = childChkBoxes.length;
            for (var i = 0; i < childChkBoxCount; i++) {
                childChkBoxes[i].checked = check;
            }
       
        function CheckUncheckParents(srcChild, check) {
            var parentDiv = GetParentByTagName("div", srcChild);
            var parentNodeTable = parentDiv.previousSibling;

            if (parentNodeTable) {
                var checkUncheckSwitch;

                if (check) //checkbox checked
                {
                    var isAllSiblingsChecked = AreAllSiblingsChecked(srcChild);
                    if (isAllSiblingsChecked)
                        checkUncheckSwitch = true;
                    else
                        return; //do not need to check parent if any(one or more) child not checked
                }
                else //checkbox unchecked
                {
                    checkUncheckSwitch = false;
                }

                var inpElemsInParentTable = parentNodeTable.getElementsByTagName("input");
                if (inpElemsInParentTable.length > 0) {
                    var parentNodeChkBox = inpElemsInParentTable[0];
                    parentNodeChkBox.checked = checkUncheckSwitch;
                    //do the same recursively
                    CheckUncheckParents(parentNodeChkBox, checkUncheckSwitch);
                }
            }
        }
        function AreAllSiblingsChecked(chkBox) {
            var parentDiv = GetParentByTagName("div", chkBox);
            var childCount = parentDiv.childNodes.length;
            for (var i = 0; i < childCount; i++) {
                if (parentDiv.childNodes[i].nodeType == 1) //check if the child node is an element node
                {
                    if (parentDiv.childNodes[i].tagName.toLowerCase() == "table") {
                        var prevChkBox = parentDiv.childNodes[i].getElementsByTagName("input")[0];
                        //if any of sibling nodes are not checked, return false
                        if (!prevChkBox.checked) {
                            return false;
                        }
                    }
                }
            }
            return true;
        }
        //utility function to get the container of an element by tagname
        function GetParentByTagName(parentTagName, childElementObj) {
            var parent = childElementObj.parentNode;
            while (parent.tagName.toLowerCase() != parentTagName.toLowerCase()) {
                parent = parent.parentNode;
            }
            return parent;
        }
    </script>