Question

When the code var accNo = '<%=Session["hdnAccession"]%>'; will be executed ?. I change the session variable in the Page_LoadComplete event, but when I access it using var accNo = '<%=Session["hdnAccession"]%>';, it always return the value which I set FIRST. In Page_LoadComplete, I do like the following… Session["hdnAccession"] = GetNewAccession(), When I debugged, I saw that the Session["hdnAccession"] updated each time. But why it do not get updated in JavaScript ?. I am in a situation where I can not use HiddenField instead of Seession.

Answer 1

You need to create a PostBack to access session variables from JS. Like so:

<script type="text/javascript">
<!--
function setSessionVariable(valueToSetTo)
{
 __doPostBack('SetSessionVariable', valueToSetTo);
}
// -->
</script>

private void Page_Load(object sender, System.EventArgs e)
{
 // Insure that the __doPostBack() JavaScript method is created...
 this.GetPostBackEventReference(this, string.Empty);

 if ( this.IsPostBack )
 {
  string eventTarget = (this.Request["__EVENTTARGET"] == null) ? string.Empty : this.Request["__EVENTTARGET"];
  string eventArgument = (this.Request["__EVENTARGUMENT"] == null) ? string.Empty : this.Request["__EVENTARGUMENT"];

  if ( eventTarget == "SetSessionVariable" )
  {
   Session["someSessionKey"] = eventArgument;
  }
 }
}

See here: http://forums.asp.net/post/2230824.aspx