add sessionExpire option

mod.ts

@@ -13,8 +13,13 @@ type HTTPServerOptions = {
   staticLocalDir?: string;
   staticServePath?: string;
   sessionSecret?: string;
+  sessionExpire?: SessionExpire | number;
 };
 
+export enum SessionExpire {
+  NEVER = 2147483647,
+}
+
 export enum HTTPMethod {
   GET = "GET",
   POST = "POST",
@@ -277,7 +282,9 @@ export class HTTPServer {
         sessionObject,
         this.settings?.sessionSecret,
       );
-      routeReply.cookie("session", encodedSession);
+      routeReply.cookie("session", encodedSession, {
+        maxAge: this.settings.sessionExpire ?? undefined,
+      });
     }
   }
 
@@ -433,9 +440,9 @@ export class RouteRequest {
         sessionCookie,
         httpServer.settings.sessionSecret,
       );
-      try{
+      try {
         this.session = JSON.parse(decodedSessionCookie);
-      }catch(_err){
+      } catch (_err) {
         // Ignore if sessionCookie is not in JSON format
       }
     }