How to set javascript function when postback occured

Hi to all,
I am Using Javascript Function for Hiding and showing a panel when user clicks a hyperlink..its working fine, but in postback event all panels automatically visible..
how to stop..it..

My Javascript Function :

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function ShowHide(id)
{
try
{
var e = document.getElementById(id);
if(e.style.display == 'block' || e.style.display=='')
e.style.display = 'none';
else
e.style.display = 'block';
}
catch(e)
{
alert( "Error in JS Function: 1" + e);
}
}

My PageLoad event :

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If Not IsPostBack Then
AddAttributes()
End If

Private Sub AddAttributes()
Try
Hplink.Attributes("onclick") = "ShowHide('Panel1');"
Hplink.Attributes("onclick") = "ShowHide('Panel2');"
Hplink.Attributes("onclick") = "ShowHide('Panel3');"
Hplink.Attributes("onmouseover") = "this.style.cursor='pointer'"
Hplink.Attributes("onmouseout") = "this.style.cursor='pointer'"
Catch ex As Exception

End Try
End Sub
pls..give code for it..
Thanks..