v12.0.0 - initial commit

packages/server/lib/event-bus.js

@@ -0,0 +1,32 @@
+// Adapted from https://medium.com/@soffritti.pierfrancesco/create-a-simple-event-bus-in-javascript-8aa0370b3969
+
+const uuid = require('uuid')
+const _ = require('lodash/fp')
+
+const subscriptions = {}
+
+function subscribe(eventType, callback) {
+  const id = uuid.v1()
+
+  if (!subscriptions[eventType]) subscriptions[eventType] = {}
+
+  subscriptions[eventType][id] = callback
+
+  return {
+    unsubscribe: () => {
+      delete subscriptions[eventType][id]
+      if (_.keys(subscriptions[eventType]).length === 0)
+        delete subscriptions[eventType]
+    },
+  }
+}
+
+function publish(eventType, arg) {
+  if (!subscriptions[eventType]) return
+
+  _.keys(subscriptions[eventType]).forEach(key =>
+    subscriptions[eventType][key](arg),
+  )
+}
+
+module.exports = { subscribe, publish }