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Getting started

eth-dagger is library for dagger project written in node.js and browser. It uses dagger server to get realtime updatesfrom Ethereum Network.

About dagger

Dagger helps users to develop faster and better Ethereum DApps. For more information:


# Using Yarn
yarn add eth-dagger

# Using NPM
npm install eth-dagger --save



Websocket: wss://
Socket: mqtts:// (You can also use `ssl://` protocol)


Websocket: wss://
Socket: mqtts:// (You can also use `ssl://` protocol)


var Dagger = require("eth-dagger");

// connect to Dagger ETH main network (network id: 1) over web socket
var dagger = new Dagger("wss://"); // dagger server

// Use mqtt protocol for node (socket)
// var dagger = new Dagger('mqtts://'); // dagger server

// get new block as soon as it gets created
dagger.on("latest:block", function(result) {
  console.log("New block created: ", result);

// get only block number (as it gets created)
dagger.on("latest:block.number", function(result) {
  console.log("Current block number: ", result);

Test dagger server

This library consists woodendagger executable which is test dagger server on your local machine. So you can test with TestRPC.

Please do not use woodendagger in production. It's only for development purpose. It doesn't support removed flag.

$ woodendagger --url= # or http://localhost:8545 for local json-rpc

# If you want to start dagger server on different ports,
# sockport: socket port for backend connection over TCP
# wsport: websocket port for frontend connection over websocket
$ woodendagger --url=http://localhost:8545 --sockport=1883 --wsport=1884

# To connect from dagger:
var dagger = new Dagger('mqtt://localhost:1883')


Ethereum events

Every ethereum event has room, and there are two rooms: latest and confirmed. latest events are fired immediately block included in chain. confirmed events are fired after 12 confirmations.

If you want to show updates on UI in your DApp, use latest events. It will help to make UI/UX better and user friendly.

Use confirmed events for irreversible tasks from server or on UI. Like sending email, notifications or allow user to do subsequent task on UI after one transaction gets confirmed.

Every event has to start with room:

// latest block number
dagger.on("latest:block.number", function(result) {
  console.log("Current block number: ",;

// confirmed (irreversible) incoming transaction
dagger.on("confirmed:addr/0xa7447.../tx/in", function(result) {
  // send email to user about new transaction she received

// confirmed (irreversible) contract deployment
dagger.on("confirmed:tx/0xd66169d..../receipt", function(result) {
  // send notification to user saying - her contract has been deployed successfully

You can use wildcard for events too. There are two type of wildcards: + (for single) and # (for multiple). Use with caution as it will fetch more data then you need, and can bombard with data to your DApp.

// Listen for every outgoing transaction for any address
dagger.on('latest:addr/+/tx/out', ...)

// Triggers when 1 GNT (Golem token) get transferred to Golem multisig wallet
dagger.on('latest:log/0xa74476443119a942de498590fe1f2454d7d4ac0d/filter/0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef/+/0x7da82c7ab4771ff031b66538d2fb9b0b047f6cf9/#', ...)

// Triggers when any amount of GNT (Golem token) get sent from Golem multisig wallet
dagger.on('latest:log/0xa74476443119a942de498590fe1f2454d7d4ac0d/filter/0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef/0x7da82c7ab4771ff031b66538d2fb9b0b047f6cf9/#', ...)

// Listen for every Golem token transfer (notice `#` at the end)
dagger.on('latest:log/0xa74476443119a942de498590fe1f2454d7d4ac0d/filter/0xddf252ad1be2c89b69c2b068fc378daa952ba7f163c4a11628f55a4df523b3ef/#', ...)
Ethereum event When? removed flag
block.number For every new block number created
block.hash For every new block hash created Yes
block For every new block created Yes
block/number When particular block in future included in chain Yes
addr/address/tx On every new transaction for address Yes
addr/address/tx/out On every new outgoing transaction for address Yes
addr/address/tx/in On every new incoming transaction for address Yes
tx/txId When given txId included in block Yes
tx/txId/success When tx status is success (included in block) for txId Yes
tx/txId/fail When tx fails (included in block) for txId Yes
tx/txId/receipt When receipt is generated (included in block) for txId Yes
addr/contractAddress/deployed When new contractAddress included in block Yes
log/contractAddress When new log generated for contractAddress Yes
log/contractAddress/filter/topic1/topic2 When new log with topic1 and topic2 generated for contractAddress Yes

Dagger events

Dagger event When? args
connection.status When connection status changes value: Boolean

Event names are case-sensitive. address, txId and topics must be in lowercase.


new Dagger(url)

Create dagger object

  • url is a String url to connect with dagger server node. Check network section for all available url values


var dagger = new Dagger(<url>);

dagger.on(event, fn)

Subscribe to a topic

  • event is a String topic to subscribe to. event wildcard characters are supported (+ - for single level and # - for multi level)
  • fn - function (data, removed) fn will be executed when event occurred:
  • data data from event
  • removed flag saying if data is removed from blockchain due to re-organization.

dagger.once(event, fn)

Same as on but will be fired only once., fn)

Unsubscribe from a topic

  • event is a String topic to unsubscribe from
  • fn - function (data, removed)


Create room out of dagger. room has to be one out of two values: latest and confirmed

  • room object has following methods:
  • on same as dagger on
  • once same as dagger once
  • off same as dagger off


Close the dagger, accepts the following options:

  • force: passing it to true will close the dagger right away. This parameter is optional.


Creates web3 contract wrapper to support dagger.

  • web3Contract: contract object web3. Example: new web3.eth.Contract(abi, address)
// web3 contract
var web3Contract = new web3.eth.Contract(abi, address);

// dagger contract
var contract = dagger.contract(web3Contract);
var filter ={
  filter: { from: "0x123456..." },
  room: "latest"
// watch, removed) {
  // : address to which it has been transferred to
  // data.returnValues.value : value which has been transferred
// watch only once
filter.watchOnce(function(data, removed) {
  // : address to which it has been transferred to
  // data.returnValues.value : value which has been transferred
// stop watching


If you have any queries, feedback or feature requests, feel free to reach out to us on telegram: