Context

Import

import { contextProvided } from '@lit-labs/context';

Signature

contextProvided(__namedParameters): (protoOrDescriptor: TODO , name?: K) => void | any

Parameters

__namedParameters

{context: {__context__: ValueType}, subscribe: boolean}

Import

import { contextProvider } from '@lit-labs/context';

Signature

contextProvider(__namedParameters): (protoOrDescriptor: TODO , name?: K) => void | any

Parameters

__namedParameters

{context: {__context__: ValueType}}

A ContextRoot can be used to gather unsatisfied context requests and re-dispatch them when new providers which satisfy matching context keys are available.

Import

import { ContextRoot } from '@lit-labs/context';

Details

This allows providers to be added to a DOM tree, or upgraded, after the consumers.

An event fired by a context requester to signal it desires a specified context with the given key.

Import

import { ContextRequestEvent } from '@lit-labs/context';

Details

A provider should inspect the context property of the event to determine if it has a value that can satisfy the request, calling the callback with the requested value if so. If the requested context event contains a truthy subscribe value, then a provider can call the callback multiple times if the value is changed, if this is the case the provider should pass an unsubscribe method to the callback which consumers can invoke to indicate they no longer wish to receive these updates. If no subscribe value is present in the event, then the provider can assume that this is a 'one time' request for the context and can therefore not track the consumer.

A callback which is provided by a context requester and is called with the value satisfying the request. This callback can be called multiple times by context providers as the requested value is changed.

Import

import { ContextCallback } from '@lit-labs/context';

Type

Interface definition for a ContextRequest

Import

import { ContextRequest } from '@lit-labs/context';

A ReactiveController which adds context consuming behavior to a custom element by dispatching context-request events.

Import

import { ContextConsumer } from '@lit-labs/context';

Details

When the host element is connected to the document it will emit a context-request event with its context key. When the context request is satisfied the controller will invoke the callback, if present, and trigger a host update so it can respond to the new value. It will also call the dispose method given by the provider when the host element is disconnected.

Import

import { Options } from '@lit-labs/context';

A ReactiveController which adds context provider behavior to a custom element.

Import

import { ContextProvider } from '@lit-labs/context';

Details

This controller simply listens to the context-request event when the host is connected to the DOM and registers the received callbacks against its observable Context implementation.

Import

import { ContextProviderEvent } from '@lit-labs/context';

Import

import { Options } from '@lit-labs/context';

Creates a typed Context.

Import

import { createContext } from '@lit-labs/context';

Signature

createContext(key): Context<K, ValueType>

Parameters

key

K

a context key value

Details

Contexts are compared with with strict equality. If you want two separate createContext() calls to referer to the same context, then use a key that will by equal under strict equality like a string for Symbol.for():

// true
createContext('my-context') === createContext('my-context')
// true
createContext(Symbol.for('my-context')) === createContext(Symbol.for('my-context'))

If you want a context to be unique so that it's guaranteed to not collide with other contexts, use a key that's unique under strict equality, like a Symbol() or object.:

// false
createContext({}) === createContext({})
// false
createContext(Symbol('my-context')) === createContext(Symbol('my-context'))

The Context type defines a type brand to associate a key value with the context value type

Import

import { Context } from '@lit-labs/context';

Type

Import

import { ContextKey } from '@lit-labs/context';

Type

A helper type which can extract a Context value type from a Context type

Import

import { ContextType } from '@lit-labs/context';

Type

A property decorator that adds a ContextConsumer controller to the component which will try and retrieve a value for the property via the Context API.

Import

import { consume } from '@lit-labs/context';

Signature

consume(__namedParameters): (protoOrDescriptor: TODO , name?: K) => void | any

Parameters

__namedParameters

{context: {__context__: ValueType}, subscribe: boolean}

A property decorator that adds a ContextConsumer controller to the component which will try and retrieve a value for the property via the Context API.

Import

import { provide } from '@lit-labs/context';

Signature

provide(__namedParameters): (protoOrDescriptor: TODO , name?: K) => void | any

Parameters

__namedParameters

{context: {__context__: ValueType}}

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