===================== Experiment Annotation ===================== This API allows privileged JavaScript to annotate the :doc:`../data/environment` with any experiments a client is participating in. The experiment annotations are sent with any ping that includes the :doc:`../data/environment` data. The JS API ========== Privileged JavaScript code can annotate experiments using the functions exposed by ``TelemetryEnvironment.sys.mjs``. The following function adds an annotation to the environment for the provided ``id``, ``branch`` and ``options``. Calling this function repeatedly with the same ``id`` will overwrite the state and trigger new subsessions (subject to throttling). ``options`` is an object that may contain ``type`` to tag the experiment with a specific type or ``enrollmentId`` to tag the enrollment in this experiment with an identifier. .. code-block:: js TelemetryEnvironment.setExperimentActive(id, branch, [options={}}]) This removes the annotation for the experiment with the provided ``id``. .. code-block:: js TelemetryEnvironment.setExperimentInactive(id) This synchronously returns a dictionary containing the information for each active experiment. .. code-block:: js TelemetryEnvironment.getActiveExperiments() .. note:: Both ``setExperimentActive`` and ``setExperimentInactive`` trigger a new subsession. However the latter only does so if there was an active experiment with the provided ``id``. Limits and restrictions ----------------------- To prevent abuses, the content of the experiment ``id`` and ``branch`` is limited to 100 characters in length. ``type`` is limited to a length of 20 characters. ``enrollmentId`` is limited to 40 characters (chosen to be just a little longer than the 36-character long GUID text representation).