JavaScript access to the blockchain
search()
This chapter describes the functions and properties related to the search() family of features.
Where the name Flowee
is used, this is the variable which results from a call similar to:
var Flowee = require('bindings')('flowee')
Flowee.search( {} )
The search function takes an object literal that can optionally have various functions and properties. Functions provided are called by the search engine when certain types of data have been found. For instance, when a new transaction has been found the user function onTxAdded()
is called with the transaction as a property.
The search object takes as input so called “jobs”. There can be many search-jobs that together make one search and the results are gathered in lists of transactions and block-headers.
The search will finish when all jobs have been completed and then the onFinished()
function is called for the user to parse the results.
Parameters
- Request Object
an object literal that will become the search object. See Request Object below.
Return-value
This function returns a promise. Notice that the promise in some cases requires at least NodeJS v12.6
Flowee.search( [] )
This is an overloaded version of the search() above, this version takes only the ‘jobs’ array as an argument.
Parameters
jobs
An array of job objects.
Return-value
This function returns a promise. Notice that in this case the promise requires at least NodeJS v12.6
Request Object
The request object is what you pass into the search, and this object is the ’this’ in the
functions, including the onFinished()
function.
Example:
Flowee.search({
jobs: [
{ // Fetch this transaction
value: txid,
type: Flowee.Job.FetchTx,
txFilter: [
Flowee.IncludeOutputAmounts, Flowee.IncludeTxId
]
}
],
onTxAdded: function(transaction) {
this.addJob({
type: Flowee.Job.FetchBlockHeader,
value: transaction.blockHeight
});
},
onFinished: function(unFinishedJobCount) { /* process results here */ }
Properties
The request object has these properties. All are optional.
jobs
This is an array of jobs. See Job for details on this class.onAddressUsedInOutput
Allows users to set a function pointer for a callback. (optional)
This function is called when a job of typeFlowee.LookupByAddress
has returned with results.
onAddressUsedInOutput: function(blockHeight, offsetInBlock, outIndex) {}
onTxAdded
Allows users to set a function pointer for a callback. (optional)
This function is called when a job of typeFlowee.FetchTx
has returned with results.
onTxAdded: function(transaction) {}
onFinished
Allows users to set a function pointer for a callback. (optional)
This function is called when all jobs have completed. The argument ‘unFinishedJobCount’ is the amount of jobs that the search didn’t manage to start. Typically due to missing properties.
onFinished: function(unFinishedJobCount) {}
onTxIdResolved
Allows users to set a function pointer for a callback. (optional)
This function is called when a job of typeFlowee.LookupTxById
has returned with results.
onTxIdResolved: function(jobId, blockHeight, offsetInBlock) {}
onSpentOutputResolved
Allows users to set a function pointer for a callback. (optional)
This function is called when a job of typeFlowee.LookupSpentTx
has returned with results.
onSpentOutputResolved: function(jobId, blockHeight, offsetInBlock) {}
onUtxoLookup
Allows users to set a function pointer for a callback. (optional)
This function is called when a job of typeFlowee.FetchUTXOUnspent
orFlowee.FetchUTXODetails
has returned with results.
onUtxoLookup: function(utxoEntry) {}
binaryHashes
Should the user set this to true the hashes (txid, previousTxid) are created as bytearrays instead of hex-strings.transactions
An array of Transaction objects, as populated by the search engine containing the actually found transactions. Consider this read-only.block$height
Each block-header that was fetched (with Flowee.FetchBlockHeader) is placed in a property with the formatblock100
for the header of the block at height 100.
Functions
addJob(job)
append a job to the jobs array. Which, if all values are provided, will be executed.
Transaction class
A transaction object is created by search and stored in an array on the Request Object under the property transactions
. Notice that based on the job.txFilter option only some of these properties may be filled in.
jobId
The index in the request objectsjobs
array that was responsible for fetching this transaction.txid
The transaction id (sha256 hash)blockHeight
The blockheight is the index of the block mined. Genesis was 11 years ago mined at block height 0, there is on average one new block added to this chain every 10 minutes.offsetInBlock
The byte-offset in the block that this transaction is located.isCoinbase
If this is a coinbase transaction, which creates new money as a block-reward, then this is set to true.inputs
An array of inputs.input.outputIndex
An index spends another transaction’s output, this indicates the output-index it spends.input.previousTxid
An index spends another transaction’s output, this indicates which transaction it spends.input.script
The input script contains the signatures and other proof that unlocks the output script it spends.input.script-array
This is the inputScript, but in array format (raw).outputs
An array of outputs.output.index
The index of the output.output.amount
The amount of money that this output spends. In satoshis. 100 000 000 satoshis go in one Bitcoin.output.script
The output script is the locking script for this output.output.script-array
This is the same outputscript, but in array format (raw).fullTxData
An array of the raw transaction data.
Blockheader
The Blockheader object is stored in block$height
named properties, on the
request-object. You’d write:
const header = result[`block${tx.blockHeight}`];
console.log(header.hash);
height
The block height is the index of the block mined. Genesis was 11 years ago mined at block height 0, there is on average one new block added to this chain every 10 minutes.confirmations
The amount of blocks mined after this block on the blockchain, more means better security. Copied at the time of running the search.hash
The block-hash.version
Block version.time
The timestamp of this block that the miner added when they created it (in seconds since epoch).mediantime
The middle time of the last 11 blocks. Which is just the block time of 6 blocks ago (in seconds since epoch).nonce
The random number added by the miner as part of the mining process.bits
The difficulty, represented in bits.difficulty
The difficulty represented in floating point.merkleroot
This blocks merkle-root.
Job
The Job object is created by users and sometimes by the framework and
typically stored on the jobs
array which is part of the request-object.
type
This has to be filled in and come from the Job-type enum.value
This contains the main value that is the input of the job. Job-type dependent.value2
This (optionally) contains another value, specific for the job-type.value3
This (optionally) contains another value, specific for the job-type.txFilter
If the job is a type that fetches transactions then this should be an array of items from the Include enum.