Javascript to validate the checkboxes on gridview for atleast one checkbox should be checked

While developing asp.net based web aplications, if our web form contains the gridview with checkboxes.
and the case is that we need to check atleast one of the checkbox from gridview. So to perform this action
using client side code we need to write javascript function for this.
So I write one small function to do this functionality in javascript.
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<script type="text/javascript">
        var TargetBaseControl = null;          

        function chkCheckBox() {                          
            TargetBaseControl = document.getElementById('<%= this.myGridview.ClientID %>');
            if (TargetBaseControl == null) return false;
            //get target child control.
            var TargetChildControl = "chkSelect";
            //get all the control of the type INPUT in the base control.
            var Inputs = TargetBaseControl.getElementsByTagName("input");

            for (var n = 0; n < Inputs.length; n++)
                if (Inputs[n].type == 'checkbox' && Inputs[n].id.indexOf(TargetChildControl, 0) >= 0 && Inputs[n].checked)
                return true;
                alert('Please select atleast one checkbox....!');
                return false;
            }
</script>
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call this function on button client click event as like below.
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 <asp:Button ID="btncall" runat="server" OnClientClick="return chkCheckBox();" Text="Call" />
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I hope this small function will help you.

Regards,
Gajanan