@adonisjs/transmit-client
v1.0.0
Published
A client for the native Server-Sent-Event module of AdonisJS.
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AdonisJS Transmit Client is a client for the native Server-Sent-Event (SSE) module of AdonisJS. It is built on top of the EventSource API and provides a simple API to receive events from the server.
Table of Contents
Installation
Install the package from the npm registry as follows:
npm i @adonisjs/transmit-client
Usage
The module exposes a Transmit
class, which can be used to connect to the server and listen for events.
import { Transmit } from '@adonisjs/transmit-client'
const transmit = new Transmit({
baseUrl: 'http://localhost:3333',
})
Creating a subscription
The subscription
method is used to create a subscription to a channel. The method accepts the channel name
const subscription = transmit.subscription('chat/1')
Then, you have to call the create
method on the subscription to register it on the backend.
await subscription.create()
You can listen for events on the channel using the onMessage
method. You can define as many listeners as you want on the same subscription.
subscription.onMessage((message) => {
console.log(message)
})
You can also listen only once for a message using the onMessagetOnce
method.
subscription.onMessageOnce((message) => {
console.log('I will be called only once')
})
Note listeners are local only; you can add them before or after registering your subscription on the server.
Unsubscribing
The onMessage
method returns a function to remove the message handler from the subscription.
const unsubscribe = subscription.onMessage(() => {
console.log('message received!')
})
// later
unsubscribe()
If you want to entirely remove the subscription from the server, you can call the delete
method.
await subscription.delete()
Subscription Request
You can alter the subscription request by using the beforeSubscribe
or beforeUnsubscribe
options.
const transmit = new Transmit({
baseUrl: 'http://localhost:3333',
beforeSubscribe: (_request: Request) => {
console.log('beforeSubscribe')
},
beforeUnsubscribe: (_request: Request) => {
console.log('beforeUnsubscribe')
},
})
Reconnecting
The transmit client will automatically reconnect to the server when the connection is lost. You can change the number of retries and hook into the reconnect lifecycle as follows:
const transmit = new Transmit({
baseUrl: 'http://localhost:3333',
maxReconnectionAttempts: 5,
onReconnectAttempt: (attempt) => {
console.log('Reconnect attempt ' + attempt)
},
onReconnectFailed: () => {
console.log('Reconnect failed')
},
})
Events
TheTransmit
class uses the EventTarget
class to emits multiple events.
transmit.on('connected', () => {
console.log('connected')
})
transmit.on('disconnected', () => {
console.log('disconnected')
})
transmit.on('reconnecting', () => {
console.log('reconnecting')
})