GitBook: [master] one page modified

Author: christianalfoni

core/running-side-effects.md

@@ -91,6 +91,7 @@ It can be a good idea to not allow your side effects to initialize when they are
 ```typescript
 import * as firebase from 'firebase'
 
+// We use IIFE to hide the private "app" variable
 export const api = (() => {
   let app
 
@@ -132,6 +133,35 @@ export const onInitialize = async ({ effects }) => {
 Typically you explicitly communicate with effects from actions, by calling methods. But sometimes you need effects to know about the state of the application, or maybe some internal state in the effect should be exposed on your application state. Again we can take advantage of an **initialize** method on the effect:
 
 {% tabs %}
+{% tab title="overmind/effects.js" %}
+```javascript
+// We use an IIFE to isolate some variables
+export const socket = (() => {
+  _options
+  _ws
+  return {
+    initialize(options) {
+      _options = options
+      _ws = new WebSocket('ws://...')
+      _ws.onclose = () => options.onStatusChange('close')
+      _ws.onopen = () => options.onStatusChange('open')
+      _ws.addEventListener(
+        'message',
+        (event) => options.onMessage(event.data)
+      )
+    },
+    send(type, data) {
+      _ws.postMessage({
+        type,
+        data,
+        token: _options.getToken()
+      })
+    }
+  }
+})()
+```
+{% endtab %}
+
 {% tab title="overmind/onInitialize.js" %}
 ```typescript
 export const onInitialize = async ({ state, effects, actions }) => {