<% response.write(var) %>
instead of
<%= var %>
FWD: http://stackoverflow.com/questions/750902/how-do-i-get-rid-of-o-is-not-declared
I've found the answer on the .net forums. It contains a good explanation of why ASP.Net is acting the way it is:
[quote]
We have finally obtained reliable repro and identified the underlying issue. A trivial repro looks like this:
<% if (true) { %>
<%=1%>
<% } %>
<%=2%>
In order to provide intellisense in <%= %> blocks at design time, ASP.NET generates assignment to a temporary __o variable and language (VB or C#) then provide the intellisense for the variable. That is done when page compiler sees the first <%= ... %> block. But here, the block is inside the if, so after the if closes, the variable goes out of scope. We end up generating something like this:
if (true) {
object @__o;
@__o = 1;
}
@__o = 2;
The workaround is to add a dummy expression early in the page. E.g. <%="" %>. This will not render anything, and it will make sure that __o is declared top level in the Render method, before any potential ‘if’ (or other scoping) statement.
[/quote]
An alternative solution is to simply use
]]>