@digicat/ethereum-contract-watcher
v1.0.0
Published
Observes contracts on a web3.js-compatible Ethereum network, providing callbacks for when events are emitted
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@digicat/ethereum-contract-watcher
This package can observe contracts on a web3.js-compatible Ethereum network, providing callbacks for when events are emitted. Requires Node.js 8.6 or newer.
Usage
const ContractWatcher = require('@digicat/ethereum-contract-watcher')
const watcher = new ContractWatcher({
ethereumNode: 'http://localhost:8545',
onError (err, token) {
// Called when an error occurred. Expected to be synchronous.
},
onEvent (event, token) {
// Called when an event occurs for a contract that's being watched.
//
// Can be asynchronous (if you return a promise). Won't interleave with
// other events.
//
// The `event` object comes directly from Web3.
// See <https://github.com/ethereum/wiki/wiki/JavaScript-API#contract-events>.
},
wrapWeb3Error (err) {
// Allows for underlying Web3 errors to be wrapped in another Error class.
// By default returns the error as-is.
return err
}
})
// Start watching a new contract. The `token` is provided in callbacks as-is.
watcher.add({
// ABI array of the contract (required).
abi: […],
// Contract address (required, no default value).
address: '0xef3b47f7e4865c72565f448cc162945ea5bcdc1e'
// The block from which events should be observed. Defaults to 'latest'.
fromBlock: 'latest',
token: {
an: {
arbitrary: 'object'
}s
}
})
// Stop watchers all contracts.
watcher.stop()