---
title: Debugging logs
description: Send debugging information in an errored response to a logging service.
image: https://edgetunnel-b2h.pages.dev/core-services-preview.png
---

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# Debugging logs

Send debugging information in an errored response to a logging service.

**JavaScript**

```js
// Replace with your actual logging service endpoint
const loggingEndpoint = "https://your-logging-endpoint";


export default {
  async fetch(request) {
    try {
      // Attempt to fetch the request from the origin server
      const response = await fetch(request.clone());


      // Check if the response status indicates an error (for example, 4xx or 5xx)
      if (!response.ok) {
        // Prepare error details and context for logging
        const errorDetails = {
          status: response.status,
          statusText: response.statusText,
          url: request.url,
          method: request.method,
          headers: Object.fromEntries(request.headers),
        };


        // Log error details to your logging service
        await logError(errorDetails);


        // Return the original response with status and statusText intact
        return new Response(response.body, {
          status: response.status,
          statusText: response.statusText,
          headers: response.headers,
        });
      }


      // Return the successful response from the origin server
      return response;
    } catch (error) {
      // Handle any exceptions that occur during fetch
      const errorDetails = {
        message: error.message,
        stack: error.stack,
        url: request.url,
        method: request.method,
        headers: Object.fromEntries(request.headers),
      };


      // Log error details to your logging service
      await logError(errorDetails);


      // Return a generic error response
      return new Response("Internal Server Error", {
        status: 500,
      });
    }
  },
};


// Function to log error details to your logging service
async function logError(details) {
  try {
    const response = await fetch(loggingEndpoint, {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify(details),
    });


    if (!response.ok) {
      console.error("Failed to log error:", response.statusText);
    }
  } catch (error) {
    console.error("Error logging error:", error.message);
  }
}
```

```json
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```