Adonis Transmit Client is a client for the native Server-Sent-Event (SSE) module of Adonis Transmit. It is built on top of the EventSource API and provides a simple API to receive events from the server.

Table of Contents

- Installation
- Usage
- Subscribing to channels
- Subscription Request
- Reconnecting
- Unsubscribing
- Events

Installation

Install the package from the npm registry as follows:

``sh
npm i @brighthustle/transmit-client

yarn

`sh

`

Usage

The module exposes a Transmit class, which can be used to connect to the server and listen for events.

`ts
import { Transmit } from '@brighthustle/transmit-client'

const transmit = new Transmit({
baseUrl: 'http://localhost:3333',
})
`

Subscribing to channels

The listenOn method accepts the channel name and a callback to be invoked when the event is received from the server.

`ts
transmit.listenOn<{ message: string }>('chat/1', (payload) => {
console.log(payload.message)
})
`

You can also listen from a channel only once.

`ts
transmit.listenOnce<{ message: string }>('chat/1', () => {
console.log('first message received!')
})
`

$3

You can alter the subscription request by using the beforeSubscribe or beforeUnsubscribe options.

`ts
const transmit = new Transmit({
baseUrl: 'http://localhost:3333',
beforeSubscribe: (_request: RequestInit) => {
console.log('beforeSubscribe')
},
beforeUnsubscribe: (_request: RequestInit) => {
console.log('beforeUnsubscribe')
},
})
`

$3

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:

`ts
const transmit = new Transmit({
baseUrl: 'http://localhost:3333',
maxReconnectionAttempts: 5,
onReconnectAttempt: (attempt) => {
console.log('Reconnect attempt ' + attempt)
},
onReconnectFailed: () => {
console.log('Reconnect failed')
},
})
`

$3

The listenOn method returns a function to unsubscribe from the channel.

`ts
const unsubscribe = transmit.listenOn('chat/1', () => {
console.log('message received!')
})

// later
unsubscribe()
`

When unsubscribing from a channel, the client will remove the local listener for that channel. By default, it will not send a request to the server when there are no more listener to unsubscribe from the channel. You can change this behavior by setting the removeSubscriptionOnZeroListener option to true.

`ts
const transmit = new Transmit({
baseUrl: 'http://localhost:3333',
removeSubscriptionOnZeroListener: true,
})
`

You can also change the default settings locally by passing a boolean to the unsubscribe method.

`ts
const unsubscribe = transmit.listenOn('chat/1', () => {
console.log('message received!')
})

// later
unsubscribe(true) // or false
`

Events

TheTransmit class extends the EventTarget class and emits multiple events.

`ts
transmit.on('connected', () => {
console.log('connected')
})

transmit.on('disconnected', () => {
console.log('disconnected')
})

transmit.on('reconnecting', () => {
console.log('reconnecting')
})
``

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