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User Guide

All information for developers using ethjs-abi should consult this document.

Install

npm install --save ethjs-abi

Usage

const abi = require('ethjs-abi');
const SimpleStoreABI = [{"constant":false,"inputs":[{"name":"_value","type":"uint256"}],"name":"set","outputs":[{"name":"","type":"bool"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"get","outputs":[{"name":"storeValue","type":"uint256"}],"payable":false,"type":"function"},{"anonymous":false,"inputs":[{"indexed":false,"name":"_newValue","type":"uint256"},{"indexed":false,"name":"_sender","type":"address"}],"name":"SetComplete","type":"event"}];


const setInputBytecode = abi.encodeMethod(SimpleStoreABI[0], [24000]);

// returns 0x60fe47b10000000000000000000000000000000000000000000000000000000000005dc0

const setOutputBytecode = abi.decodeMethod(SimpleStoreABI[0], "0x0000000000000000000000000000000000000000000000000000000000000001");

// returns  Result { '0': true }



const getInputBytecode = abi.encodeMethod(SimpleStoreABI[1], []);

// returns 0x6d4ce63c

const getMethodOutputBytecode = abi.decodeMethod(SimpleStoreABI[1], "0x000000000000000000000000000000000000000000000000000000000000b26e");

// returns Result { '0': <BN: b26e>, storeValue: <BN: b26e> }

const SetCompleteInputBytecode = abi.encodeEvent(SimpleStoreABI[2], [24000, "0xca35b7d915458ef540ade6068dfe2f44e8fa733c"]);

// returns 0x10e8e9bc0000000000000000000000000000000000000000000000000000000000005dc0000000000000000000000000ca35b7d915458ef540ade6068dfe2f44e8fa733c

const event = abi.decodeEvent(SimpleStoreABI[2], "0x0000000000000000000000000000000000000000000000000000000000000d7d000000000000000000000000ca35b7d915458ef540ade6068dfe2f44e8fa733c");

/* returns   Result {
  '0': <BN: d7d>,
  '1': '0xca35b7d915458ef540ade6068dfe2f44e8fa733c',
  _newValue: <BN: d7d>,
  _sender: '0xca35b7d915458ef540ade6068dfe2f44e8fa733c' }
*/

const event = abi.decodeLogItem(SimpleStoreABI[2], receipt.log[0]);

/* returns   Result {
  '0': <BN: d7d>,
  '1': '0xca35b7d915458ef540ade6068dfe2f44e8fa733c',
  _newValue: <BN: d7d>,
  _sender: '0xca35b7d915458ef540ade6068dfe2f44e8fa733c' }
*/

const decoder = abi.logDecoder(SimpeStoreABI)

const events = decoder(receipt.logs)
/* returns   Result [{
  '0': <BN: d7d>,
  '1': '0xca35b7d915458ef540ade6068dfe2f44e8fa733c',
  _newValue: <BN: d7d>,
  _sender: '0xca35b7d915458ef540ade6068dfe2f44e8fa733c' 
}]
*/

BN

This module returns BNs for all quantity values. However, the module supports both BN.js and BigNumber.js modules for encoding, but will only return BN instances while decoding.

Safe Object Returns (decoding)

Instead of returning an array of params as decoded from the method, ethjs-abi will return a safe object that allows you to both get a value at it's return index or optionally, its name.

For example:

{
  '0': <BN: d7d>,
  '1': '0xca35b7d915458ef540ade6068dfe2f44e8fa733c',
  _newValue: <BN: d7d>,
  _sender: '0xca35b7d915458ef540ade6068dfe2f44e8fa733c' }

Why BN.js?

ethjs has made a policy of using BN.js across all of its repositories. Here are some of the reasons why:

  1. lighter than alternatives (BigNumber.js)
  2. faster than most alternatives, see benchmarks
  3. used by the Ethereum foundation across all ethereumjs repositories
  4. is already used by a critical JS dependency of many ethereum packages, see package elliptic
  5. purposefully does not support decimals or floats numbers (for greater precision), remember, the Ethereum blockchain cannot and will not support float values or decimal numbers.

Browser Builds

ethjs provides production distributions for all of its modules that are ready for use in the browser right away. Simply include either dist/ethjs-abi.js or dist/ethjs-abi.min.js directly into an HTML file to start using this module. Note, an ethAbi object is made available globally.

<script type="text/javascript" src="ethjs-abi.min.js"></script>
<script type="text/javascript">
new ethAbi(...);
</script>

Note, even though ethjs should have transformed and polyfilled most of the requirements to run this module across most modern browsers. You may want to look at an additional polyfill for extra support.

Use a polyfill service such as Polyfill.io to ensure complete cross-browser support: https://polyfill.io/

Latest Webpack Figures

Hash: 492bde711463f9215365                                                           
Version: webpack 2.1.0-beta.15
Time: 1066ms
           Asset    Size  Chunks             Chunk Names
    ethjs-abi.js  186 kB       0  [emitted]  main
ethjs-abi.js.map  228 kB       0  [emitted]  main
    + 14 hidden modules

Hash: a5dc8d1c909ad22a89ba                                                           
Version: webpack 2.1.0-beta.15
Time: 4291ms
           Asset     Size  Chunks             Chunk Names
ethjs-abi.min.js  83.1 kB       0  [emitted]  main
    + 14 hidden modules

Other Awesome Modules, Tools and Frameworks

Foundation

  • web3.js -- the original Ethereum JS swiss army knife Ethereum Foundation
  • ethereumjs -- critical ethereum javascript infrastructure Ethereum Foundation
  • browser-solidity -- an in browser Solidity IDE Ethereum Foundation

Nodes

  • geth Go-Ethereum
  • parity Rust-Ethereum build in Rust
  • testrpc Testing Node (ethereumjs-vm)

Testing

  • wafr -- a super simple Solidity testing framework
  • truffle -- a solidity/js dApp framework
  • embark -- a solidity/js dApp framework
  • dapple -- a solidity dApp framework
  • chaitherium -- a JS web3 unit testing framework
  • contest -- a JS testing framework for contracts

Wallets

  • ethers-wallet -- an amazingly small Ethereum wallet
  • metamask -- turns your browser into an Ethereum enabled browser =D

Our Relationship with Ethereum & EthereumJS

We would like to mention that we are not in any way affiliated with the Ethereum Foundation or ethereumjs. However, we love the work they do and work with them often to make Ethereum great! Our aim is to support the Ethereum ecosystem with a policy of diversity, modularity, simplicity, transparency, clarity, optimization and extensibility.

Many of our modules use code from web3.js and the ethereumjs- repositories. We thank the authors where we can in the relevant repositories. We use their code carefully, and make sure all test coverage is ported over and where possible, expanded on.