The Prometheus Team has commented that certain features are missing from the prom-client that would give it full parity with the existing clients.

The initial plan for this release is to do a best effort to reach feature parity with the other clients.

Things we will likely not be implementing would include:

• deprecated features
• experimental features

Things that will likely be pushed to a v2 milestone would include:

• features that overlap with each other

It is better for client_js to ship a version that provides at least one implementation for each of the major workflows of a telemetry library than that it duplicate the entire API of other clients at the expense of shipping much later. Feature-for-feature duplication can be a target for v2 and v3 releases.