fixed file request

static/script.js

@@ -54,12 +54,18 @@ const sendRequest = async (request, mode) => {
         body: JSON.stringify(request)
       });
     } else {
+      const formData = new FormData();
+
+      // Append all properties of the request object to the FormData
+      for (const key in request) {
+        if (request.hasOwnProperty(key)) {
+          formData.append(key, request[key]);
+        }
+      }
+
       response = await fetch('/predict_batch', {
         method: 'POST',
-        headers: {
-          'Content-Type': 'application/json'
-        },
-        body: JSON.stringify(request)
+        body: formData
       });
     }