diff --git a/.gitignore b/.gitignore
index 128f0f9..82be075 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,2 +1,4 @@
 /node_modules/
 /static/
+/.log/
+/yarn-error.log
diff --git a/Docker/utils.sh b/Docker/utils.sh
index ba26708..30add45 100644
--- a/Docker/utils.sh
+++ b/Docker/utils.sh
@@ -83,6 +83,7 @@ prepare_firefox(){
   keycombo Shift_L F5 #profiler
   grab "after shift-c F5"
   keycombo Control_L Shift_L e
+  sleep 5 # it needs some time
 }
 
 load_website(){
diff --git a/index.js b/index.js
index 22ccf7f..b1fa55d 100644
--- a/index.js
+++ b/index.js
@@ -32,23 +32,12 @@ function attach(docker_id, output_stream) {
     output_stream.push(d);
   });
   task.on("close", () => {
-    const check = spawn("docker", ["ps", "--filter", `id=${docker_id}`]);
-    let output = "";
-    check.on("data", (data) => {
-      output += data;
-    });
-    check.on("close", () => {
-      console.log("CHECK", output);
-      clearInterval(interval);
-    });
-    check.on("error", (error) => {
-      console.error("error", error);
-      clearInterval(interval);
-    });
-    check.on("exit", (error) => {
-      console.error("exit", error);
-      clearInterval(interval);
-    });
+    output_stream.push("</pre>");
+    output_stream.push(/* HTML */ `<script>
+      clearInterval(window.interval);
+    </script>`);
+    clearInterval(interval);
+    output_stream.push(null);
   });
 }
 
@@ -64,7 +53,7 @@ router.get("/", async (ctx) => {
     `<img id="preview" width="1080" height="608" src="/static/${id}/preview.png?id=0"/><br/>`
   );
   ctx.body.push(/* HTML */ `<script>
-    setInterval(() => (preview.src = preview.src + "0"), 500);
+    window.interval = setInterval(() => (preview.src = preview.src + "0"), 500);
   </script>`);
   const params = qs.parse(ctx.querystring);
   s.push(`Got request to screenshot ${params.url}<pre>`);