---
lang: en
title: 'API docs: context.context.notifyobservers'
keywords: LoopBack 4.0, LoopBack 4
sidebar: lb4_sidebar
permalink: /doc/en/lb4/apidocs.context.context.notifyobservers.html
---

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[Home](./index.md) &gt; [@loopback/context](./context.md) &gt; [Context](./context.context.md) &gt; [notifyObservers](./context.context.notifyobservers.md)

## Context.notifyObservers() method

Publish an event to the registered observers. Please note the notification is queued and performed asynchronously so that we allow fluent APIs such as `ctx.bind('key').to(...).tag(...);` and give observers the fully populated binding.

<b>Signature:</b>

```typescript
protected notifyObservers(eventType: ContextEventType, binding: Readonly<Binding<unknown>>, context: Context, observers?: Set<ContextEventObserver> | undefined): Promise<void>;
```

## Parameters

|  Parameter | Type | Description |
|  --- | --- | --- |
|  eventType | <code>ContextEventType</code> | Event names: <code>bind</code> or <code>unbind</code> |
|  binding | <code>Readonly&lt;Binding&lt;unknown&gt;&gt;</code> | Binding bound or unbound |
|  context | <code>Context</code> | Owner context |
|  observers | <code>Set&lt;ContextEventObserver&gt; &#124; undefined</code> | Current set of context observers |

<b>Returns:</b>

`Promise<void>`