@chamaeleonidae/amplitude-plugin

Amplitude Browser SDK destination plugin that intercepts $identify events and forwards user attributes to Chameleon via chmln.identify().

Install

npm install @chamaeleonidae/amplitude-plugin

Usage

import * as amplitude from '@amplitude/analytics-browser';
import { ChameleonPlugin } from '@chamaeleonidae/amplitude-plugin';

amplitude.add(new ChameleonPlugin('YOUR_CHAMELEON_TOKEN'));
amplitude.init('YOUR_AMPLITUDE_API_KEY');

The Chameleon SDK (chmln.js) must be loaded on the page. If window.chmln is not yet available when an $identify event fires, the plugin queues the call and polls with exponential backoff (~4 seconds total) until the SDK loads.

How it works

When Amplitude dispatches an $identify event, the plugin:

1. Extracts user_properties operations ($set, $setOnce, $unset)
2. Merges them with the following precedence: $unset > $set > $setOnce
3. Prefixes every key with amplitude_ (e.g. plan becomes amplitude_plan)
4. Calls chmln.identify(user_id, prefixed_properties)

$unset handling

Keys in $unset are mapped to null, which tells Chameleon to clear those attributes. $unset has the highest precedence — if a key appears in both $set and $unset, it will be set to null.

Limitations

• $add is not supported. Amplitude's $add operation (increment numeric values) is silently ignored. Only $set, $setOnce, and $unset are forwarded.
• No backfill. The plugin only captures users who trigger a new $identify call after installation. Existing Amplitude user attributes are not retroactively synced. To backfill a specific user, trigger an identify call:

const identifyEvent = new amplitude.Identify();
identifyEvent.set('plan', 'enterprise');
amplitude.identify(identifyEvent);

Development

bun install
bun run test
bun run build