ethereumjs-abi

Module implementing the Ethereum ABI in Javascript. Can be used with RPC libraries for communication or with ethereumjs-vm to implement a fully fledged simulator.

Usage

There are two methods of interest, rawEncode to encode a call (name plus arguments) and rawDecode to decode a response for a specific encoded query.

Example code:

var ABI = require('ethereumjs-abi');
var abi = new ABI();

// returns the encoded binary (as a Buffer) data to be sent
var encoded = abi.rawEncode("balanceOf", [ "address" ], [ "0x0000000000000000000000000000000000000000" ]);

// returns the decoded array of arguments
// need to define the input argument list in order to select the proper function
var decoded = abi.rawDecode("balanceOf", [ "address" ], [ "uint256" ], data);

For preparing encoded blocks without the signature, use rawEncodeResponse. This can be useful when interfacing with contracts as a data provider.

Planned for the future is supporting the JSON ABI definition:

var ABI = require('ethereumjs-abi');
var abi = new ABI();

// need to have the ABI definition in JSON as per specification
var tokenAbi = [{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"balanceOf","outputs":[{"name":"","type":"uint256"}],"type":"function"},{"constant":false,"inputs":[{"name":"_to","type":"address"},{"name":"_value","type":"uint256"}],"name":"transfer","outputs":[{"name":"success","type":"bool"}],"type":"function"},{"inputs":[],"type":"constructor"}];

var encoded = ABI.encode(tokenAbi, "balanceOf(uint256 address)", [ "0x0000000000000000000000000000000000000000" ]);

var decoded = ABI.decode(tokenAbi, "balanceOf(uint256 address)", data);

Contributing

I am more than happy to receive improvements. Please send me a pull request or reach out on email or twitter.

There is a lot missing, grep for FIXME in the source code to find inspiration.

License

Copyright (C) 2015 Alex Beregszaszi

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
the Software, and to permit persons to whom the Software is furnished to do so,
subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.