Thin WebSocket adapter with auto-reconnect and offline buffering
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readme.md

TOC

Overview

Webbs is a thin abstraction over the WebSocket API available in modern browsers. It provides vital missing features: automatic reconnect with exponential backoff, and offline buffering of outgoing messages.

Small (≈ 180 LoC, 2.4 KiB minified), dependency-free, simple, hackable.

Installation

Webbs is meant for a CommonJS-compatible bundler, such as Webpack or browserify. Install it from NPM:

npm i -E webbs
# or
yarn add -E webbs

Then import:

import {Webbs} from 'webbs'

API

Webbs()

Creates a new instance. It starts blank and inert. You must call .open(url, protocol) to actually open a connection.

import {Webbs} from 'webbs'

const webbs = new Webbs()

webbs.onEachOpen =
webbs.onEachClose =
webbs.onEachError =
webbs.onEachMessage =
function report(event) {
  console.info('Something happened:', event)
}

webbs.open('ws://my-host:my-port', 'optional-protocol')

webbs.state

Always one of: 'CLOSED', 'CONNECTING', 'OPEN'. Initially 'CLOSED'.

webbs.open(url, protocol)

Opens the connection. Will automatically reconnect if disconnected. Stores webbs.url and webbs.protocol for automatic reconnects. Idempotent: has no effect if already connected.

const webbs = new Webbs()
webbs.open('ws://my-host:my-port', 'optional-protocol')

webbs.close()

Empties the outgoing message buffer, closes the connection, and doesn't reconnect. Can be reopened later. Will trigger onEachClose if the underlying websocket is open.

Also aliased as webbs.deinit.

webbs.close()
// some time later
webbs.open(webbs.url, webbs.protocol)

webbs.deinit()

Same as .close(). Aliased for compatibility with my other libraries, where deinit is the dominant interface for "closing" things.

webbs.send(message)

Sends message over the websocket, if open. The message must be compatible with WebSocket.prototype.send (string or blob).

If not connected, adds message to webbs.outgoingBuffer. When connected, will send all buffered messages at once.

const webbs = new Webbs()

// These get buffered
webbs.send('my msg')
webbs.send(new Blob([1, 2, 3]))

// If this succeeds, the messages will be automatically sent
webbs.open('ws://my-host:my-port')

webbs.onEachOpen

Initially undefined; you can assign a function. Gets called whenever an underlying native websocket successfully connects. May be triggered multiple times over the lifetime of the webbs instance.

webbs.onEachOpen = function report(event) {
  console.info('Socket reconnected:', event)
}

webbs.onEachClose

Initially undefined; you can assign a function. Gets called whenever an underlying native websocket closes. May be triggered multiple times over the lifetime of the webbs instance.

Counter-intuitively, this doesn't have symmetry with .onEachOpen. When reconnecting, .onEachClose will be called on each failed attempt.

Calling webbs.close() or webbs.deinit() always triggers onEachClose. If the underlying websocket was open, it's triggered asynchronously and receives the relevant DOM event. If the websocket wasn't open, it's triggered synchronously and receives undefined.

webbs.onEachClose = function report(event) {
  console.warn('Socket disconnected:', event)
}

webbs.onEachError

Initially undefined; you can assign a function. Gets called whenever an underlying native websocket fails to connect or loses an active connection. May be triggered multiple times over the lifetime of the webbs instance.

webbs.onEachError = function report(event) {
  console.warn('Socket error:', event)
}

webbs.onEachMessage

Initially undefined; you can assign a function. Gets called whenever an underlying native websocket receives a message.

webbs.onEachMessage = function report(event) {
  console.info('Socket message:', event)
}

Changelog

0.0.9

Better minification. Slightly breaking.

  • use ES5-style class to avoid Babel garbage in the output
  • replaced webbs.getState() with the webbs.state getter
  • 2.6 KiB → 2.4 KiB

0.0.8

Breaking improvements and cleanup:

  • moved url and protocol arguments from constructor to .open
  • .close and .deinit are now equivalent
  • added webbs.getState
  • better ordering of state changes and callbacks; a webbs instance now reaches a consistent state before invoking the corresponding onEach callback
  • onEachClose is always called on .close, even if there was no underlying socket
  • removed sendJson; just define a function if you want

Misc

I'm receptive to suggestions. If this library almost satisfies you but needs changes, open an issue or chat me up. Contacts: https://mitranim.com/#contacts