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---
lang: en
title: 'API docs: context.context'
keywords: LoopBack 4.0, LoopBack 4, Node.js, TypeScript, OpenAPI
sidebar: lb4_sidebar
editurl: https://github.com/loopbackio/loopback-next/tree/master/packages/context
permalink: /doc/en/lb4/apidocs.context.context.html
---
<!-- Do not edit this file. It is automatically generated by API Documenter. -->
[Home](./index.md) > [@loopback/context](./context.md) > [Context](./context.context.md)
## Context class
Context provides an implementation of Inversion of Control (IoC) container
<b>Signature:</b>
```typescript
export declare class Context extends EventEmitter
```
<b>Extends:</b> EventEmitter
## Constructors
| Constructor | Modifiers | Description |
| --- | --- | --- |
| [(constructor)(\_parent, name)](./context.context._constructor_.md) | | Create a new context. |
## Properties
| Property | Modifiers | Type | Description |
| --- | --- | --- | --- |
| [\_debug](./context.context._debug.md) | | Debugger | A debug function which can be overridden by subclasses. |
| [\_parent?](./context.context._parent.md) | | [Context](./context.context.md) | <i>(Optional)</i> Parent context |
| [configResolver](./context.context.configresolver.md) | | [ConfigurationResolver](./context.configurationresolver.md) | Configuration resolver |
| [name](./context.context.name.md) | | string | Name of the context |
| [registry](./context.context.registry.md) | | Map<string, [Binding](./context.binding.md)<!-- -->> | Key to binding map as the internal registry |
| [scope](./context.context.scope.md) | | [BindingScope](./context.bindingscope.md) | Scope for binding resolution |
| [subscriptionManager](./context.context.subscriptionmanager.md) | | [ContextSubscriptionManager](./context.contextsubscriptionmanager.md) | Manager for observer subscriptions |
| [tagIndexer](./context.context.tagindexer.md) | | ContextTagIndexer | Indexer for bindings by tag |
## Methods
| Method | Modifiers | Description |
| --- | --- | --- |
| [\_findByTagIndex(tag)](./context.context._findbytagindex.md) | | Find bindings by tag leveraging indexes |
| [\_mergeWithParent(childList, parentList)](./context.context._mergewithparent.md) | | |
| [add(binding)](./context.context.add.md) | | Add a binding to the context. If a locked binding already exists with the same key, an error will be thrown. |
| [bind(key)](./context.context.bind.md) | | Create a binding with the given key in the context. If a locked binding already exists with the same key, an error will be thrown. |
| [close()](./context.context.close.md) | | Close the context: clear observers, stop notifications, and remove event listeners from its parent context. |
| [configure(key)](./context.context.configure.md) | | Create a corresponding binding for configuration of the target bound by the given key in the context.<!-- -->For example, <code>ctx.configure('controllers.MyController').to({x: 1})</code> will create binding <code>controllers.MyController:$config</code> with value <code>{x: 1}</code>. |
| [contains(key)](./context.context.contains.md) | | Check if a binding exists with the given key in the local context without delegating to the parent context |
| [createView(filter, comparator, options)](./context.context.createview.md) | | Create a view of the context chain with the given binding filter |
| [debug(args)](./context.context.debug.md) | | Wrap the debug statement so that it always print out the context name as the prefix |
| [emitError(err)](./context.context.emiterror.md) | | Emit an <code>error</code> event |
| [emitEvent(type, event)](./context.context.emitevent.md) | | A strongly-typed method to emit context events |
| [find(pattern)](./context.context.find.md) | | Find bindings using a key pattern or filter function |
| [findByTag(tagFilter)](./context.context.findbytag.md) | | Find bindings using the tag filter. If the filter matches one of the binding tags, the binding is included. |
| [findOrCreateBinding(key, policy)](./context.context.findorcreatebinding.md) | | Find or create a binding for the given key |
| [get(keyWithPath, session)](./context.context.get.md) | | Get the value bound to the given key, throw an error when no value is bound for the given key. |
| [get(keyWithPath, options)](./context.context.get_1.md) | | Get the value bound to the given key, optionally return a (deep) property of the bound value. |
| [getBinding(key)](./context.context.getbinding.md) | | Look up a binding by key in the context and its ancestors. If no matching binding is found, an error will be thrown. |
| [getBinding(key, options)](./context.context.getbinding_1.md) | | Look up a binding by key in the context and its ancestors. If no matching binding is found and <code>options.optional</code> is not set to true, an error will be thrown. |
| [getConfig(key, propertyPath, resolutionOptions)](./context.context.getconfig.md) | | Resolve configuration for the binding by key |
| [getConfigAsValueOrPromise(key, propertyPath, resolutionOptions)](./context.context.getconfigasvalueorpromise.md) | | Get the value or promise of configuration for a given binding by key |
| [getConfigSync(key, propertyPath, resolutionOptions)](./context.context.getconfigsync.md) | | Resolve configuration synchronously for the binding by key |
| [getDebugNamespace()](./context.context.getdebugnamespace.md) | | Get the debug namespace for the context class. Subclasses can override this method to supply its own namespace. |
| [getOwnerContext(keyOrBinding)](./context.context.getownercontext.md) | | Get the owning context for a binding or its key |
| [getResolutionContext(binding)](./context.context.getresolutioncontext.md) | | Locate the resolution context for the given binding. Only bindings in the resolution context and its ancestors are visible as dependencies to resolve the given binding |
| [getScopedContext(scope)](./context.context.getscopedcontext.md) | | Get the context matching the scope |
| [getSync(keyWithPath, session)](./context.context.getsync.md) | | Get the synchronous value bound to the given key, optionally return a (deep) property of the bound value.<!-- -->This method throws an error if the bound value requires async computation (returns a promise). You should never rely on sync bindings in production code. |
| [getSync(keyWithPath, options)](./context.context.getsync_1.md) | | Get the synchronous value bound to the given key, optionally return a (deep) property of the bound value.<!-- -->This method throws an error if the bound value requires async computation (returns a promise). You should never rely on sync bindings in production code. |
| [inspect(options)](./context.context.inspect.md) | | Inspect the context and dump out a JSON object representing the context hierarchy |
| [isBound(key)](./context.context.isbound.md) | | Check if a key is bound in the context or its ancestors |
| [isSubscribed(observer)](./context.context.issubscribed.md) | | Check if an observer is subscribed to this context |
| [isVisibleTo(ctx)](./context.context.isvisibleto.md) | | Check if this context is visible (same or ancestor) to the given one |
| [on(eventName, listener)](./context.context.on.md) | | The "bind" event is emitted when a new binding is added to the context. The "unbind" event is emitted when an existing binding is removed. |
| [on(event, listener)](./context.context.on_1.md) | | |
| [once(eventName, listener)](./context.context.once.md) | | The "bind" event is emitted when a new binding is added to the context. The "unbind" event is emitted when an existing binding is removed. |
| [once(event, listener)](./context.context.once_1.md) | | |
| [setupConfigurationResolverIfNeeded()](./context.context.setupconfigurationresolverifneeded.md) | | Set up the configuration resolver if needed |
| [subscribe(observer)](./context.context.subscribe.md) | | Add a context event observer to the context |
| [toJSON()](./context.context.tojson.md) | | Create a plain JSON object for the context |
| [unbind(key)](./context.context.unbind.md) | | Unbind a binding from the context. No parent contexts will be checked. |
| [unsubscribe(observer)](./context.context.unsubscribe.md) | | Remove the context event observer from the context |