0.0.2 • Public • Published

Build Status NPM


General purpose library for EOSIO blockchains.


EOSIO/eosjs Npm EOSIO/eos Docker Hub
tags: 16.0.0 - 16.0.6 npm install eosjs tags: v1.1.n - v1.2.1 eosio/eos:v1.2.1

Prior version matrix.


  • Install with: npm install eosjs
  • Html script tag, see releases for the correct version and its matching script integrity hash.
sha512-1+9QoHM15or8AQMLftEEACcwATU38fqGn1q8NiZ6ybA6fFGWSrdx7ppR859TEwYQAASIUpi7fd8UzQZfqLA6pQ== lib/eos.js
sha512-IS9vyI+sMK7MYNJgHj9G8Li21QYs59sRW/Nyzi+dKUh6bF6OfpOnvzSCTiegWftY1ozOmmyacCH2QIJpZgbuKw== lib/eos.min.js
sha512-g905cUn6OWkdrFTNXd87/ZvTpOHKM0/sOhcGsnS+BFQZ0pp2+KnO6SWg/HdgB/tDvOEm6zSY8p8+/H99cteGPQ== lib/eos.min.js.map
  <meta charset="utf-8">
  <script src="https://cdn.jsdelivr.net/npm/eosjs@16.0.6/lib/eos.min.js"
  /** Transactions are only valid on the selected chain. */
  chain = {
    main: 'aca376f206b8fc25a6ed44dbdc66547c36c6c33e3a119ffbeaef943642f0e906', // main network
    jungle: '038f4b0fc8ff18a4f0842a8f0564611f6e96e8535901dd45e43ac8691a1c4dca', // jungle testnet
    sys: 'cf057bbfb72640471fd910bcb67639c22df9f92470936cddc1ade0e2f2e7dc4f' // local developer
    Other httpEndpoint's: https://www.eosdocs.io/resources/apiendpoints
  eos = Eos({
    keyProvider: '5KQwrPbwdL6PhXujxW37FSSQZ1JiwsST4cqQzDeyXtP79zkvFD3',// private key
    httpEndpoint: '',
    chainId: chain.sys,
    Sign and broadcast a transaction.
    @example updateProducerVote('myaccount', 'proxyaccount', ['respectedbp'])
  async function updateProducerVote(voter, proxy = '', producers = []) {
    return eos.voteproducer(voter, proxy, producers)


Ways to instantiate eosjs.

Eos = require('eosjs')
// Private key or keys (array) provided statically or by way of a function.
// For multiple keys, the get_required_keys API is used (more on that below).
keyProvider: '5KQwrPbwdL6PhXujxW37FSSQZ1JiwsST4cqQzDeyXtP79zkvFD3'
// Localhost Testnet (run ./docker/up.sh)
eos = Eos({keyProvider})
// Connect to a testnet or mainnet
eos = Eos({httpEndpoint, chainId, keyProvider})
// Cold-storage
eos = Eos({httpEndpoint: null, chainId, keyProvider})
// Add support for non-EOS public key prefixes, such as PUB, etc
eos = Eos({keyPrefix: 'PUB'})
// Read-only instance when 'eosjs' is already a dependency
eos = Eos.modules.api({/*config*/})
// Read-only instance when an application never needs to write (smaller library)
EosApi = require('eosjs-api')
eos = EosApi({/*config*/})

No-arguments prints usage.

getBlock - Fetch a block from the blockchain.
  "block_num_or_id": "string"

Start a nodeosd process. The docker in this repository provides a setup that supports the examples in this README.

cd ./docker && ./up.sh

All blockchain functions (read and write) follow this pattern:

// If the last argument is a function it is treated as a callback
eos.getBlock(1, (error, result) => {})
// If a callback is not provided, a Promise is returned
eos.getBlock(1) // @returns {Promise}
// Parameters can be positional or an object
eos.getBlock({block_num_or_id: 1})
// An API with no parameters is invoked with an empty object or callback (avoids logging usage)
eos.getInfo({}) // @returns {Promise}
eos.getInfo((error, result) => { console.log(error, result) })

API Documentation

Chain and history API functions are available after creating the eos object.


Eos = require('eosjs')
// Default configuration
config = {
  chainId: null, // 32 byte (64 char) hex string
  keyProvider: ['PrivateKeys...'], // WIF string or array of keys..
  httpEndpoint: '',
  expireInSeconds: 60,
  broadcast: true,
  verbose: false, // API activity
  sign: true
eos = Eos(config)
  • chainId hex - Unique ID for the blockchain you're connecting to. This is required for valid transaction signing. The chainId is provided via the get_info API call.

    Identifies a chain by its initial genesis block. All transactions signed will only be valid the blockchain with this chainId. Verify the chainId for security reasons.

  • keyProvider [array<string>|string|function] - Provides private keys used to sign transactions. If multiple private keys are found, the API get_required_keys is called to discover which signing keys to use. If a function is provided, this function is called for each transaction.

    If a keyProvider is not provided here, one may be provided on a per-action or per-transaction basis in Options.

  • keyPrefix [string='EOS'] - Change the public key prefix.

  • httpEndpoint string - http or https location of a nodeosd server providing a chain API. When using eosjs from a browser remember to configure the same origin policy in nodeosd or proxy server. For testing, nodeosd configuration access-control-allow-origin = * could be used.

    Set this value to null for a cold-storage (no network) configuration.

  • expireInSeconds number - number of seconds before the transaction will expire. The time is based on the nodeosd's clock. An unexpired transaction that may have had an error is a liability until the expiration is reached, this time should be brief.

  • broadcast [boolean=true] - post the transaction to the blockchain. Use false to obtain a fully signed transaction.

  • verbose [boolean=false] - verbose logging such as API activity.

  • debug [boolean=false] - low level debug logging (serialization).

  • sign [boolean=true] - sign the transaction with a private key. Leaving a transaction unsigned avoids the need to provide a private key.

  • mockTransactions (advanced)

    • mockTransactions: () => null // 'pass', or 'fail'
    • pass - do not broadcast, always pretend that the transaction worked
    • fail - do not broadcast, pretend the transaction failed
    • null|undefined - broadcast as usual
  • transactionHeaders (advanced) - manually calculate transaction header. This may be provided so eosjs does not need to make header related API calls to nodeos. Used in environments like cold-storage. This callback is called for every transaction. Headers are documented here eosjs-api#headers.

    • transactionHeaders: (expireInSeconds, callback) => {callback(null/*error*/, headers)}
  • logger - default logging configuration.

    logger: {
      log: config.verbose ? console.log : null,  // null to disable
      error: config.verbose ? console.error : null,

    For example, redirect error logs: config.logger = {error: (...args) => ..}

  • authorization - replace the default eosjs authorization on actions. An authorization provided here may still be over-written by specifying an authorization for each individual action.

    For example, if most actions in an dapp are based on the posting key, this would replace the default active authorization with a posting authorization:

    {authorization: '@posting'}


Options may be provided after parameters.

NOTE: authorization is for individual actions, it does not belong in Eos(config).

options = {
  authorization: 'alice@active',
  broadcast: true,
  sign: true
eos.transfer('alice', 'bob', '1.0000 SYS', '', options)
  • authorization [array<auth>|auth] - identifies the signing account and permission typically in a multisig configuration. Authorization may be a string formatted as account@permission or an object<{actor: account, permission}>.

    • If missing default authorizations will be calculated.
    • If provided additional authorizations will not be added.
    • Performs deterministic sorting by account name

    If a default authorization is calculated the action's 1st field must be an account_name. The account_name in the 1st field gets added as the active key authorization for the action.

  • broadcast [boolean=true] - post the transaction to the blockchain. Use false to obtain a fully signed transaction.

  • sign [boolean=true] - sign the transaction with a private key. Leaving a transaction unsigned avoids the need to provide a private key.

  • keyProvider [array<string>|string|function] - just like the global keyProvider except this provides a temporary key for a single action or transaction.

    await eos.anyAction('args', {keyProvider})
    await eos.transaction(tr => { tr.anyAction() }, {keyProvider})


The transaction function accepts the standard blockchain transaction.

Required transaction header fields will be added unless you are signing without a network connection (httpEndpoint == null). In that case provide you own headers:

// only needed in cold-storage or for offline transactions
const headers = {
  expiration: '2018-06-14T18:16:10',
  ref_block_num: 1,
  ref_block_prefix: 452435776

Create and send (broadcast) a transaction:

/** @return {Promise} */
    // ...headers,
    // context_free_actions: [],
    actions: [
        account: 'eosio.token',
        name: 'transfer',
        authorization: [{
          actor: 'inita',
          permission: 'active'
        data: {
          from: 'inita',
          to: 'initb',
          quantity: '7.0000 SYS',
          memo: ''
  // config -- example: {broadcast: false, sign: true}

Named action functions

More concise functions are provided for applications that may use actions more frequently. This avoids having lots of JSON in the code.

// Run with no arguments to print usage.
// Callback is last, when omitted a promise is returned
eos.transfer('inita', 'initb', '1.0000 SYS', '', (error, result) => {})
eos.transfer('inita', 'initb', '1.1000 SYS', '') // @returns {Promise}
// positional parameters
eos.transfer('inita', 'initb', '1.2000 SYS', '')
// named parameters
eos.transfer({from: 'inita', to: 'initb', quantity: '1.3000 SYS', memo: ''})
// options appear after parameters
options = {broadcast: true, sign: true}
// `false` is a shortcut for {broadcast: false}
eos.transfer('inita', 'initb', '1.4000 SYS', '', false)

Read-write API methods and documentation are generated from the eosio token and system.

Assets amounts require zero padding. For a better user-experience, if you know the correct precision you may use DecimalPad to add the padding.

DecimalPad = Eos.modules.format.DecimalPad
userInput = '10.2'
precision = 4
assert.equal('10.2000', DecimalPad(userInput, precision))

For more advanced signing, see keyProvider and signProvider in index.test.js.


Shorthand is available for some types such as Asset and Authority. This syntax is only for concise functions and does not work when providing entire transaction objects to eos.transaction..

For example:

  • permission inita defaults inita@active
  • authority 'EOS6MRy..' expands {threshold: 1, keys: [{key: 'EOS6MRy..', weight: 1}]}
  • authority inita expands {threshold: 1, accounts: [{permission: {actor: 'inita', permission: 'active'}, weight: 1}]}

New Account

New accounts will likely require some staked tokens for RAM and bandwidth.

wif = '5KQwrPbwdL6PhXujxW37FSSQZ1JiwsST4cqQzDeyXtP79zkvFD3'
pubkey = 'EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV'
eos.transaction(tr => {
    creator: 'eosio',
    name: 'myaccount',
    owner: pubkey,
    active: pubkey
    payer: 'eosio',
    receiver: 'myaccount',
    bytes: 8192
    from: 'eosio',
    receiver: 'myaccount',
    stake_net_quantity: '10.0000 SYS',
    stake_cpu_quantity: '10.0000 SYS',
    transfer: 0


Deploy and call smart contracts.


If you're loading a wasm file, you do not need binaryen. If you're loading a wast file you can include and configure the binaryen compiler, this is used to compile to wasm automatically when calling setcode.

Versions of binaryen may be problematic.

$ npm install binaryen@37.0.0
binaryen = require('binaryen')
eos = Eos({keyProvider, binaryen})


wasm = fs.readFileSync(`docker/contracts/eosio.token/eosio.token.wasm`)
abi = fs.readFileSync(`docker/contracts/eosio.token/eosio.token.abi`)
// Publish contract to the blockchain
eos.setcode('myaccount', 0, 0, wasm) // @returns {Promise}
eos.setabi('myaccount', JSON.parse(abi)) // @returns {Promise}

Fetch a smart contract

// @returns {Promise}
eos.contract('myaccount', [options], [callback])
// Run immediately, `myaction` returns a Promise
eos.contract('myaccount').then(myaccount => myaccount.myaction(..))
// Group actions. `transaction` returns a Promise but `myaction` does not
eos.transaction('myaccount', myaccount => { myaccount.myaction(..) })
// Transaction with multiple contracts
eos.transaction(['myaccount', 'myaccount2'], ({myaccount, myaccount2}) => {

Offline or cold-storage contract

eos = Eos({httpEndpoint: null})
abi = fs.readFileSync(`docker/contracts/eosio.token/eosio.token.abi`)
eos.fc.abiCache.abi('myaccount', JSON.parse(abi))
// Check that the ABI is available (print usage)
eos.contract('myaccount').then(myaccount => myaccount.create())

Offline or cold-storage transaction

// Prepare headers
expireInSeconds = 60 * 60 // 1 hour
eos = Eos(/* {httpEndpoint: 'https://..'} */)
info = await eos.getInfo({})
chainDate = new Date(info.head_block_time + 'Z')
expiration = new Date(chainDate.getTime() + expireInSeconds * 1000)
expiration = expiration.toISOString().split('.')[0]
block = await eos.getBlock(info.last_irreversible_block_num)
transactionHeaders = {
  ref_block_num: info.last_irreversible_block_num & 0xFFFF,
  ref_block_prefix: block.ref_block_prefix
// OFFLINE (bring `transactionHeaders`)
// All keys in keyProvider will sign.
eos = Eos({httpEndpoint: null, chainId, keyProvider, transactionHeaders})
transfer = await eos.transfer('inita', 'initb', '1.0000 SYS', '')
transferTransaction = transfer.transaction
// ONLINE (bring `transferTransaction`)
eos = Eos(/* {httpEndpoint: 'https://..'} */)
processedTransaction = await eos.pushTransaction(transferTransaction)
// cleos version:
const cleosTransaction = transferTransaction.transaction
cleosTransaction.signatures = transferTransaction.signatures
// `cloes push transaction ${JSON.stringify(cleosTransaction)}`

Custom Token

// more on the contract / transaction syntax
await eos.transaction('myaccount', myaccount => {
  // Create the initial token with its max supply
  // const options = {authorization: 'myaccount'} // default
  myaccount.create('myaccount', '10000000.000 PHI')//, options)
  // Issue some of the max supply for circulation into an arbitrary account
  myaccount.issue('myaccount', '10000.000 PHI', 'issue')
const balance = await eos.getCurrencyBalance('myaccount', 'myaccount', 'PHI')
console.log('Currency Balance', balance)

Calling Actions

Other ways to use contracts and transactions.

// if either transfer fails, both will fail (1 transaction, 2 messages)
await eos.transaction(eos =>
    eos.transfer('inita', 'initb', '1.0000 SYS', ''/*memo*/)
    eos.transfer('inita', 'initc', '1.0000 SYS', ''/*memo*/)
    // Returning a promise is optional (but handled as expected)
  // [options],
  // [callback]
// transaction on a single contract
await eos.transaction('myaccount', myaccount => {
  myaccount.transfer('myaccount', 'inita', '10.000 PHI', '')
// mix contracts in the same transaction
await eos.transaction(['myaccount', 'eosio.token'], ({myaccount, eosio_token}) => {
  myaccount.transfer('inita', 'initb', '1.000 PHI', '')
  eosio_token.transfer('inita', 'initb', '1.0000 SYS', '')
// The contract method does not take an array so must be called once for
// each contract that is needed.
const myaccount = await eos.contract('myaccount')
await myaccount.transfer('myaccount', 'inita', '1.000 PHI', '')
// a transaction to a contract instance can specify multiple actions
await myaccount.transaction(myaccountTr => {
  myaccountTr.transfer('inita', 'initb', '1.000 PHI', '')
  myaccountTr.transfer('initb', 'inita', '1.000 PHI', '')


From time-to-time the eosjs and nodeos binary format will change between releases so you may need to start nodeos with the --skip-transaction-signatures parameter to get your transactions to pass.

Note, package.json has a "main" pointing to ./lib. The ./lib folder is for es2015 code built in a separate step. If you're changing and testing code, import from ./src instead.

Eos = require('./src')
// forceActionDataHex = false helps transaction readability but may trigger back-end bugs
config = {verbose: true, debug: false, broadcast: true, forceActionDataHex: true, keyProvider}
eos = Eos(config)


The eos instance can provide serialization:

// 'asset' is a type but could be any struct or type like: transaction or uint8
type = {type: 1, data: '00ff'}
buffer = eos.fc.toBuffer('extensions_type', type)
assert.deepEqual(type, eos.fc.fromBuffer('extensions_type', buffer))
// ABI Serialization
eos.contract('eosio.token', (error, eosio_token) => {
  create = {issuer: 'inita', maximum_supply: '1.0000 SYS'}
  buffer = eosio_token.fc.toBuffer('create', create)
  assert.deepEqual(create, eosio_token.fc.fromBuffer('create', buffer))

Use Node v10+ for package-lock.json.

Related Libraries

These libraries are integrated into eosjs seamlessly so you probably do not need to use them directly. They are exported here giving more API access or in some cases may be used standalone.

var {format, api, ecc, json, Fcbuffer} = Eos.modules
  • format ./format.md

    • Blockchain name validation
    • Asset string formatting
  • eosjs-api [Github, NPM]

    • Remote API to an EOS blockchain node (nodeos)
    • Use this library directly if you need read-only access to the blockchain (don't need to sign transactions).
  • eosjs-ecc [Github, NPM]

    • Private Key, Public Key, Signature, AES, Encryption / Decryption
    • Validate public or private keys
    • Encrypt or decrypt with EOS compatible checksums
    • Calculate a shared secret
  • json {api, schema},

    • Blockchain definitions (api method names, blockchain schema)
  • eosjs-keygen [Github, NPM]

    • private key storage and key management
  • Fcbuffer [Github, NPM]

    • Binary serialization used by the blockchain
    • Clients sign the binary form of the transaction
    • Allows client to know what it is signing


Node and browser (es2015)

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