hiding clearing controls on client side

i have all controls in update panel

when grid header is clicked it causes asynchronous post backto the serverside code which has

div1.Attributes["style"] = "display:block";

the control become visible

along with this div control i have a OK client side button which has when clicked

 document.getElementById('div1').style.display = "none";     

al the above working fine

but when any other postback happens the  above control id dsiplayed

if grid header is clicked it causes asynchronous post & others causes full postback i had the code to check the same & accrodingly make them

which shld not be div1.Attributes["style"] = "display:none";

but still they are displayed

i need it to be displayed only on gridheader click , nothing else