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Example code

Labeling internal and external traffic​

Suppose you want to extend your events with a label that distinguishes traffic from internal and external systems. This is a good use case for adding an entity.

const internalIPs = new Set([

function process(event) {
const ip = event.getUser_ipaddress();
const traffic_source = internalIPs.has(ip) ? 'internal' : 'external';

return [{
schema: "",
data: { traffic_source }

This example is not copy-paste-able. You will need to define your own schema.

Filtering out bots​

You can use the IAB enrichment to identify bots. However, it does not remove the bot-generated events from your data β€” it only adds relevant information to the events (in the derived_contexts field), e.g.:

"schema": "iglu:com.iab.snowplow/spiders_and_robots/jsonschema/1-0-0",
"data": {
"spiderOrRobot": false,
"category": "BROWSER",
"reason": "PASSED_ALL",
"primaryImpact": "NONE"

If you wish to discard the bot events (sending them to failed events), you can use the JavaScript enrichment:

function process(event) {
const entities = JSON.parse(event.getDerived_contexts());
if (entities) {
for (const entity of {
if (entity.schema.startsWith('iglu:com.iab.snowplow/spiders_and_robots/jsonschema/1') && {
throw "Filtered a spider/bot event";

You need to use Enrich 3.8.0+ (or Snowplow Micro 1.7.1+) to be able to access the derived entities via event.getDerived_contexts(). In prior versions, this function always returns null.

For special cases, you can also dispense with the IAB enrichment and add something simpler:

const botPattern = /.*Googlebot.*/;

function process(event) {
const useragent = event.getUseragent();

if (useragent !== null && botPattern.test(useragent)) {
throw "Filtered event produced by Googlebot";

Omitting information based on a condition​

Let’s say you want to omit certain user information depending on which country the user is in. While PII pseudonymization enrichment is very useful for dealing with PII, it does not support such conditions. JavaScript enrichment to the rescue!

function process(event) {
if (event.getGeo_country() === 'US') {
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