> For clean Markdown of any page, append .md to the page URL. > For a complete documentation index, see https://akamai.ferndocs.com/llms.txt. > For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://akamai.ferndocs.com/_mcp/server. # JavaScript Logging details You can deliver the JavaScript logs via [Enhanced debug headers](enable-enhanced-debug-headers.md) or a [DataStream 2](/edge-workers/ds2-javascript-logging). # Enhanced debug header logging details Each event handler returns a corresponding response header. A response header is only returned when logging information is available for the event. The log header name starts with X-Akamai-EdgeWorker: - X-Akamai-EdgeWorker-onClientRequest-Log - X-Akamai-EdgeWorker-onOriginRequest-Log - X-Akamai-EdgeWorker-onClientResponse-Log - X-Akamai-EdgeWorker-onOriginResponse-Log - X-Akamai-EdgeWorker-responseProvider-Log You can also add the `X-Akamai-EdgeWorker-subworkers-Log` request header to limit which EdgeWorkers collect JavaScript logs. This can help you stay with the JavaScript Logging limits. For more information go to [subWorkers JavaScript Logging details](javascript-logging-details-copy.md#javascript-logging-for-subworkers). > 📘 You can configure the JavaScript logs to appear in an [LDS server log](https://techdocs.akamai.com/log-delivery/docs) or a [DataStream 2 log](datastream-2-integration.md). ## Enhanced debug header logging format EdgeWorkers JavaScript logging returns logs in the following format ``:``:`` ``.
JavaScript Logging fields Details Description
<debug-level>:<file>:<line>:<message> <debug-level> The debug level specified in the request request header. T- Trace D - Debug I - Info W - Warn E - Error
<file> The URL encoded file name is only included if it is different from the previous log line.
<line> The line number where the log was executed.
<message> The URL encoded message. Includes values for any data included in the message. A vertical bar (|) separates multiple messages. - All text in the string is ASCII. Invalid characters and delimiters are percent encoded. - A dollar sign appends text truncated by the byte limit.
# Data Stream 2 JavaScript logging details You can generate these logs by following the steps in the [Use DataStream 2 to deliver JavaScript logs](javascript-logging.md) tutorial. The following is an example of the JSON data output by DataStream 2. If you select the JSON output option for your logs, `timestamp` and `version` are renamed to `time` and `format` to facilitate the naming conventions of specific endpoints. ```json [ { "severity": "ERROR", "time": "1718023875520000000", "version": "1", "body": "onClientRequest%20test%20%20error%20level", "ds2id": "71321", "format": "1", "attributes": { "request_id": "1a1a1a1", "nl": "1", }, "resource": { "cloud.provider": "AkamaiEdgeWorkers", "ew": "42", "ewv": "0.9", "ip": "" } } ] ``` ## Data Stream 2 logging format EdgeWorkers JavaScript logging returns logs in the following format, `timestamp` `version` `ds2id` `severity` `traceid` `spanid` `traceflags` `resource` `attributes` `body`. | Data Stream 2 logging field | Description | | --- | --- | | `severity` | The available severity levels are TRACE, DEBUG, INFO, WARN, and ERROR. | | `timestamp` or
`time` for JSON log output | Time of event handler initialization. | | `version` or `format` for JSON output | A version number specifying the format of the log line for accurate parsing.
The initial value is 1. | | `ds2id` | Corresponds to the `streamId` identified in the EdgeWorkers code bundle. This is same streamID you can use for API calls such as, `get-stream`. | | `traceid` | Currently unused field. Reserved for future use with Open Telemetry standard. | | `spanid` | Currently unused field. Reserved for future use with Open Telemetry standard. | | `traceflags` | Currently unused field. Reserved for future use with Open Telemetry standard. | | `resource` | Describes information about the source of the log such as the `ip`, `cloud.provider`, `ew_id`, `ew_version`. | | `attributes` | Additional information about the specific event occurrence. You can use this field to correlate other log entries saved for the same request.

It also includes an `nl` flag if the number of logging messages sent within one second is close to the [limit](limitations.md#limits-for-javascript-logs-delivered-via-datastream-2) . For example, `nl:1`. | | `body` | You can include any text here. The body is delivered as URL encoded data and remains encoded until it reaches the destination endpoints. Protobuf supports formatted JSON. | ## DataStream 2 and the EdgeWorkers access model For an EdgeWorker to access a DataStream 2 object it has to be part of or share access to common group. This means that the EdgeWorker needs to be: - A member of the same group as the Data Stream 2 object. - Or in a group that belongs to the one that the Data Stream 2 object is assigned to. You cannot use a DataStream 2 stream for log delivery if the EdgeWorker does not meet the Access control requirements. For more information go to the [Identity and Access Management](https://techdocs.akamai.com/iam/docs/about-access-control-model) guide. ## DataStream 2 log delivery You can deliver the log entries in up to two separate streams. - In the `bundle.json` file in the EdgeWorkers [code bundle](https://techdocs.akamai.com/edgeworkers/docs/code-bundle-format). - Via the [EdgeWorkers CLI](https://techdocs.akamai.com/edgeworkers/docs/akamai-cli) where you can add additional independent streams to deliver logs. If you configure the streams independently from each other, you can apply different log level filters.