websocket-promise-lite

What is it?

This is an Axios for WebSockets :-)

For what?

To easily work with sockets in async / await style.

Installation

npm i websocket-promise-lite

How to use?

import WebsocketPromiseLiteClient from 'websocket-promise-lite'

const demoFunc = async () => {
	const WS = new WebsocketPromiseLiteClient({
		url: 'wss://ws.postman-echo.com/raw'
	})
	await WS.connectionEstablished()
	const answer = await WS.send({
		myMessage: 'hello websocket!'
	})
	console.log(answer)

	// next actions ...

	WS.close()
}

demoFunc()

Important!

Back-end (websocket server) have to answer with the same "messageId" parameter!

API

methods

• connectionEstablished: waits for the connection to be established. If fails it reconnects automatically
• send: sends any unserialized object by WS
• close: closes WS at normal way (code 1000)
• destroy: destructor. Removes all event listeners, closes WS connection and clears the list of operations

const WS = new WebsocketPromiseLiteClient(config)

where config is an object with a possible properties:

Config parameters

url: WebSocket URL. Must start with "ws://" or "wss://". The only required param

maxNumberOfReconnects: maximum number of reconnections, after which there will be no more reconnections. If -1 then will be no reconnections. Default Infinity.

pauseBetweenReconnects: pause between reconnections (in ms). If 0 then reconnections will become after randomized pause. Pauses are stored in array [xyz, 3xyz, 5xyz, 8xyz, 12xyz, 17xyz ... 17xyz], where xyz is random number. This is so that all clients reconnects at different time for stable back-end. Default 0.

connectTimeout: time in ms after which connection is considered unsuccessful (and then reconnects again). Default 5000.

serializer: serializer function. For example, CBOR.encode. Default JSON.stringify.

deserializer: deserializer function. For example, CBOR.decode. Default JSON.parse.

binaryType: type of data to be transmitted. In most cases it's "arraybuffer". But You may specify it as blob. Default arraybuffer.

urlAdditionalGenerator: use it when second url part have to be generated by some algorythm. Pass a function.

onConnectionOpen: function (async or not) which is called when a connection is opened successfully for a 1st time

onConnectionClose: function (async or not) which is called when a connection is closed.

onConnectionReOpen: function (async or not) which is called when a connection is before reopen.

onBeforeReOpen: function (async or not) which is called when a connection is before reopen.

onNotPromisedData: function (async or not) which is called when server sends not promised data (simple WS data from back-end)

Tips

• Don't serialize data before sending via websocket-promise-lite. All the data is serialized by lib before sending.
• Library adds "messageId" field to object You are sending. Make sure Your data object has no field with the same name.