web3-tools

A collection of tools to interact with the Ethereum blockchain through a web3 instance.

Installation

$3

npm install --save web3-tools

$3

Browser package is currently not available. Stay tuned. For now, you can use browserify.

Usage

The library is initialized with a web3 instance. It exports an object with uncomplicated, easy to use functions.

``js
const web3 = someWeb3Instance // requires web3 1.0
const {deployContract, sendTransaction} = require('web3-tools')(web3)
`

All functions of the library return a promise that resolves to a transaction receipt as soon as the contract is mined. A transaction receipt (for example for contract deployment) looks like this:

`js
{ blockHash: '0x2e16f86b70d4c8f89f442295584017590b7b3ac0d27847b0e04df64bd5aa7a89',
blockNumber: 4652060,
contractAddress: '0x86Af6004557039b52666b0B58eb052E6Ddeeb1Af',
cumulativeGasUsed: 1649769,
gasUsed: 1649769,
logs: [],
logsBloom: '0x00000....',
root: null,
status: null,
transactionHash: '0xb9de15fc9197d0501873445674b253aa0469e8e50d090609b80082bc503733d7',
transactionIndex: 0 }
`

$3

Deploy a contract on the blockchain.

#### Parameters

1. options
- options.contractJSON: The compiled JSON of the contract
- options.from: The contract creator address. Use your public ethereum address here.
- options.fromKey: The private key belonging to the creator.
- options.args: Arguments passed to the constructor.
- options.maxGas: The maximum amount of gas to pay. Promise will reject if too low.

#### Returns

A promise that resolves to the transaction receipt when the transaction is mined.

#### Example

`js
let options = {
maxGas: 3000000,
contractJSON: fs.readFileSync("./mycontract.json").toString(),
from: '0x11b1EeC366d1e79923c15514f1B8C014Ce780c8D',
fromKey: Buffer.from('f8ce489f073b6aa62b8841894e42b0fac0b522185dc350af0a4f2ce3b43633a9', 'hex'),
args: []
}

deployContract(options)
.then(function(receipt) {
console.log('Contract deployed at ' + receipt.contractAddress)
})
.catch(console.error)
`

$3

Call a method of a deployed contract. Will send a transaction to the network.

#### Parameters

1. options
- options.methodName: The name of the method to be called
- options.contractAddress: The address of the contract
- options.contractABI: The compiled ABI of the contract
- options.from: The caller address. Use your public ethereum address here.
- options.fromKey: The private key belonging to the caller.
- options.args: Array of arguments to be passed to the method.
- options.maxGas: The maximum amount of gas to pay. Promise will reject if too low.

#### Returns

A promise that resolves to the transaction receipt when the transaction is mined.

#### Example

`js
let options = {
maxGas: 10000,
methodName: 'sendTokens',
contractAddress: '0x6dc1733d8c009e908274c055e2656ad3f45a860f',
contractABI: fs.readFileSync("./mycontract.abi").toString(),
from: '0x11b1EeC366d1e79923c15514f1B8C014Ce780c8D',
fromKey: Buffer.from('f8ce489f073b6aa62b8841894e42b0fac0b522185dc350af0a4f2ce3b43633a9', 'hex'),
args: ['0x11b1EeC366d1e79923c15514f1B8C014Ce780c8D', 100]
}

sendTransaction(options)
.then(function(receipt) {
console.log('Done')
})
.catch(console.error)
``

Contributing

We could use some tests. Pull requests are welcome.