Check/uncheck CheckBox in a GridView using Javascript

        function checkStatus(id)
        {
            //get reference of GridView control
            var grid = document.getElementById("<%= GridView1.ClientID %>");
            //variable to contain the cell of the grid
            var cell;
	    var statusCheck = true;

            
            if (grid.rows.length > 0)
            {
                //loop starts from 1. rows[0] points to the header.
                for (i=1; i<grid.rows.length; i++)
                {
                    //get the reference of first column
                    cell = grid.rows[i].cells[0];
                    
                    //loop according to the number of childNodes in the cell
                    for (j=0; j<cell.childNodes.length; j++)
                    {           
                        //if childNode type is CheckBox                 
                        if (cell.childNodes[j].type =="checkbox")
                        {
                        	if (cell.childNodes[j].checked == false)
				{
					statusCheck = false;
					break;
				}

                        }
                    }
                }

		if (statusCheck)
			//change the status of the Select All checkbox
			document.getElementById(id).checked = true;
		else
			document.getElementById(id).checked = false;
            }
        }

    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
	string cbSelectAllClientID = "";
        
	if (e.Row.RowType == DataControlRowType.Header)
        { 
            //Find the checkbox control in header and add an attribute
            ((CheckBox)e.Row.FindControl("cbSelectAll")).Attributes.Add("onclick", "javascript:SelectAll('" + 
                    ((CheckBox)e.Row.FindControl("cbSelectAll")).ClientID + "')");

            cbSelectAllClientID = ((CheckBox)e.Row.FindControl("cbSelectAll")).ClientID;
        }

	if (e.Row.RowType == DataControlRowType.DataRow)
	{
	    //Here the checkboxes have an id cbStatus
	    ((CheckBox)e.Row.FindControl("cbStatus")).Attributes.Add("onclick", "javascript:checkStatus('" + 
                    cbSelectAllClientID + "')");
	}
    }

<script type="text/javascript">
//<![CDATA[
function SelectAll(GridName,SelectAll) 
{
	 var grid = document.getElementById(GridName);
	 var cell;
	 if (grid.rows.length > 0)
	 {
		 for (i=1; i		 {
			 cell = grid.rows[i].cells[0];
			 for (j=0; j			 {
				 if (cell.childNodes[j].type =="checkbox")
				 {
					 cell.childNodes[j].checked = document.getElementById(SelectAll).checked;
				 }
			 }
		 }
	 }
}
//]]>
</script>

		
			

                                                                    <input id="ctl00_ContentPlaceHolder1_grdMandatesList_ctl01_chkSelectAll" type="checkbox" name="ctl00$ContentPlaceHolder1$grdMandatesList$ctl01$chkSelectAll"  önclick="javascript:SelectAll(ctl00_ContentPlaceHolder1_grdMandatesList,ctl00_ContentPlaceHolder1_grdMandatesList_ctl01_chkSelectAll);" />

protected void Page_Load(object sender, EventArgs e)
{
            if (!Page.IsPostBack)
            {
                LoadMandatesList();
            }
            if (!Page.ClientScript.IsClientScriptBlockRegistered("MandateSelectAll"))
            {
                string strScript = Global.GetSelectAllScript();
                Page.ClientScript.RegisterClientScriptBlock(this.GetType(), "MandateSelectAll", strScript, true);
            } //I have also tried it by putting this in the code-behind of the master page 
}
protected void LoadMandatesList()
{
            BindMandateList(0);
}
private void BindMandateList(int intNewPageIndex)
        {
            g_dtMandatesList = (GlobalVariables.g_AccessLevel == 1 || GlobalVariables.g_AccessLevel == 2) ?
                Mandate.GetMandatesList(g_AgencyID) : Mandate.GetMandatesList(g_AgencyID, g_AgentID);
            Global.BindGridView(ref grdMandatesList, g_dtMandatesList, intNewPageIndex);
        }

protected void grdMandatesList_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.Header)
            {
                string strGridName = grdMandatesList.ClientID, strSelectAll = ((CheckBox)e.Row.FindControl("chkSelectAll")).ClientID;
                string strJavascript = "javascript:SelectAll(" + strGridName + "," + strSelectAll + ")";
                ((CheckBox)e.Row.FindControl("chkSelectAll")).Attributes.Add("onclick", strJavascript);
            }
}

public static string GetSelectAllScript()
        {
            StringBuilder strRefreshScript = new StringBuilder();
            strRefreshScript.Append("function SelectAll(GridName,SelectAll) \n");
            strRefreshScript.Append("{\n");
            strRefreshScript.Append("\t var grid = document.getElementById(GridName);\n");
            strRefreshScript.Append("\t var cell;\n");
            strRefreshScript.Append("\t if (grid.rows.length > 0)\n");
            strRefreshScript.Append("\t {\n");
            strRefreshScript.Append("\t\t for (i=1; i<grid.rows.length;>            strRefreshScript.Append("\t\t\t for (j=0; j<cell.childnodes.length;>            strRefreshScript.Append("\t\t\t\t {\n");
            strRefreshScript.Append("\t\t\t\t\t cell.childNodes[j].checked = document.getElementById(SelectAll).checked;\n");
            strRefreshScript.Append("\t\t\t\t }\n");
            strRefreshScript.Append("\t\t\t }\n");
            strRefreshScript.Append("\t\t }\n");
            strRefreshScript.Append("\t }\n");
            strRefreshScript.Append("}\n");            
        }
}

Error: missing ; before statement
Source File: javascript: Error: ctl00_ContentPlaceHolder1_grdMandatesList is not defined

Source Code:
 Error: ctl00_ContentPlaceHolder1_grdMandatesList is not defined

<%@ Master Language="C#" AutoEventWireup="true" CodeFile="MasterPage.master.cs" Inherits="MasterPage" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>Untitled Page</title>
    
    <script type="text/javascript">
        function SelectAll(id, gridId)
        {
            //get reference of GridView control
            var grid = document.getElementById(gridId);
            //variable to contain the cell of the grid
            var cell;
            
            if (grid.rows.length > 0)
            {
                //loop starts from 1. rows[0] points to the header.
                for (i=1; i<grid.rows.length; i++)
                {
                    //get the reference of first column
                    cell = grid.rows[i].cells[0];
                    
                    //loop according to the number of childNodes in the cell
                    for (j=0; j<cell.childNodes.length; j++)
                    {           
                        //if childNode type is CheckBox                 
                        if (cell.childNodes[j].type =="checkbox")
                        {
                        //assign the status of the Select All checkbox to the cell checkbox within the grid
                            cell.childNodes[j].checked = document.getElementById(id).checked;
                        }
                    }
                }
            }
        }
    </script>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <asp:contentplaceholder id="ContentPlaceHolder1" runat="server">
        </asp:contentplaceholder>
    </div>
    </form>
</body>
</html>

<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" AutoEventWireup="true" CodeFile="Default2.aspx.cs" Inherits="Default2" Title="Untitled Page" %>
<asp:Content ID="Content1" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">

<div>
        <asp:GridView ID="GridView1" runat="server" AutoGenerateColumns="False" OnRowDataBound="GridView1_RowDataBound">
            <Columns>
                <asp:TemplateField>
                    <AlternatingItemTemplate>
                        <asp:CheckBox ID="cbSelectAll" runat="server" />
                    </AlternatingItemTemplate>
                    <HeaderTemplate>
                        <asp:CheckBox ID="cbSelectAll" runat="server" Text="Select All" />
                    </HeaderTemplate>
                    <ItemTemplate>
                        <asp:CheckBox ID="cbSelectAll" runat="server" />
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:BoundField DataField="ApplicationName" HeaderText="Application Name" />
                <asp:BoundField DataField="ServerName" HeaderText="Server Name" />
            </Columns>
        </asp:GridView>
    
    </div>
</asp:Content>

public partial class Default2 : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            //Binding GridView with the datasource
            this.GridView1.DataSource = FillDataTable();
            this.GridView1.DataBind();
        }
    }

    /// <summary>
    /// Method that will add few rows in a DataTable and returns a DataTable
    /// </summary>
    /// <returns>DataTable</returns>
    protected DataTable FillDataTable()
    {
        DataTable dt = new DataTable();
        dt.Columns.Add("ApplicationID");
        dt.Columns.Add("ApplicationName");
        dt.Columns.Add("ServerName");

        DataRow dr = dt.NewRow();
        dr[0] = "1";
        dr[1] = "Application 1";
        dr[2] = "Server 1";
        dt.Rows.Add(dr);

        DataRow dr1 = dt.NewRow();
        dr1[0] = "2";
        dr1[1] = "Application 2";
        dr1[2] = "Server 2";
        dt.Rows.Add(dr1);

        DataRow dr2 = dt.NewRow();
        dr2[0] = "3";
        dr2[1] = "Application 3";
        dr2[2] = "Server 3";
        dt.Rows.Add(dr2);

        DataRow dr3 = dt.NewRow();
        dr3[0] = "4";
        dr3[1] = "Application 4";
        dr3[2] = "Server 4";
        dt.Rows.Add(dr3);

        DataRow dr4 = dt.NewRow();
        dr4[0] = "5";
        dr4[1] = "Application 5";
        dr4[2] = "Server 5";
        dt.Rows.Add(dr4);

        DataRow dr5 = dt.NewRow();
        dr5[0] = "6";
        dr5[1] = "Application 6";
        dr5[2] = "Server 6";
        dt.Rows.Add(dr5);

        return dt;
    }
    protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        if (e.Row.RowType == DataControlRowType.Header)
        {
            //Find the checkbox control in header and add an attribute
            ((CheckBox)e.Row.FindControl("cbSelectAll")).Attributes.Add("onclick", "javascript:SelectAll('" +
                ((CheckBox)e.Row.FindControl("cbSelectAll")).ClientID + "','" + this.GridView1.ClientID + "')");
        }
    }
}