Utilities¶

const utils = require('@browseth/utils');

or

import utils from '@browseth/utils';

Array Buffers¶

An Array Buffer is an Array Buffer.

^utils.ab . isBytes ( value [, length] ): Checks to see if value is bytes and if it matches optional length
^utils.ab . fromView ( view ): Returns an Array Buffer from view
^utils.ab . fromBytes ( value [, length] ): Returns Array Buffer from bytes with optional length
^utils.ab . fromUtf8 ( value ): Returns Array Buffer from fromUtf8
^utils.ab . fromUInt ( value ): Returns Array Buffer from UInt
^utils.ab . toUf8 ( value ): Converts Array Buffer into Utf8
^utils.ab . toTwos ( value, size ): Converts Array Buffer into a two’s compliment
^utils.ab . stripStart ( value ): Strips out the start of an Array Buffer
^utils.ab . padStart ( value, length [, fillByte] ): Pads the start of an Array Buffer
^utils.ab . padEnd ( value, length [, fillByte] ): Pads the end of an Array Buffer
^utils.ab . concat ( values ): Concats an array of Array Buffers

Address¶

Utilities for manipulating addresses

^{utils.address} . isValid ( value ): Checks if the given value is a valid address
^{utils.address} . from ( value ): Returns an address from bytes
^{utils.address} . fromAddressAndNonce ( address, nonce ): Returns an address from an address and nonce

Crypto¶

^utils.crypto . keccak256 ( value ): returns the keccak256 of a string
^utils.crypto . uuid ( value ): TODO: uuid is meant for internal use. Not working externally yet. returns the uuid of a string

Interval¶

^{utils.interval} . setUnrefedInterval ( fn, delay [, args] ): Sets an interval that dies when the function it’s wrapped in is finished
^{utils.interval} . setUnrefedTimeout ( fn, delay [, args] ): Sets a timeout that dies when the function it’s wrapped in is finished

Param¶

^utils.param . toData ( value, length ): Converts parameters to hex
^utils.param . toQuantity ( value ): Converts parameters to hex string quantity
^utils.param . toTag ( value ): Converts value into a tag
^utils.param . isData ( value [, length] ): Checks if value is data of optional length
^utils.param . isQuantity ( value ): Checks if value is a quantity
^utils.param . isTag ( value ): Checks if value is a tag
^utils.param . fromData ( value, length ): Converts value to uint8Array of length
^utils.param . fromQuantity ( value ): Converts quantity to Big Number
^utils.param . fromTag ( value ): Converts tag to Big Number

RLP¶

RLP (Recursive Length Prefix) is the main encoding method used to serialize objects in Ethereum

^utils.rlp . encode ( value ): Encodes value to Array Buffer
^utils.rlp . encodeLength ( len, offset ): Encodes length to Array Buffer with offset

Block Tracker¶

Poll for blocks every 5 seconds until a block number is confirmed. Use this class to keep track of block(s). Contains #emitter.

Creating Instances¶

new ^{Browseth.utils} . BlockTracker ( requestQueue [, confirmationDelay = 0] ): Request queue is an eth reference. The confirmation delay is the minimum number of confirmed blocks until the block is considered confirmed.

Prototype¶

^prototype . addTracker ( key [, options] )

Track a block.

Options may have the following properties:

synced – ‘latest’, ‘earliest’, or block # to track (defaults to ‘latest’)
confirmationDelay – minimum # of confirmed blocks until tracked block is considered confirmed

^prototype . syncBlockNumber ( )

Sets the latest block number

emits ‘block.number’ with block # passed to the event callback

See #emitter

^prototype . syncBlocks ( )

Syncs blocks to latest block

emits ‘block’ for every synced block - block is passed to the event callback

See #emitter

Transaction Listener¶

Monitor transactions

Creating Instances¶

new ^{Browseth.utils} . TxListener ( ethRef ): Create new TxListener object with eth reference.

Prototype¶

^prototype . listen ( txHash ): <Promise>

Listen for a transaction until it is mined. Returns a promise that resolves to a transaction receipt.

If the listener does not see a receipt after 30 minutes it throws assuming the transaction has been dropped from the network

Example¶

import Browseth from '@browseth/browser'

const beth = new Browseth('https://mainnet.infura.io');
beth.useOnlineAccount();

const txListener = new Browseth.utils.TxListener(beth);

txListener.listen(txHash)
    .then(receipt => console.log(receipt))
    .catch(e => console.log('Transaction dropped!'))

Observable¶

Subscribe to value changes with callbacks

Creating Instances¶

new ^{Browseth.utils} . Observable ( value ): Create new Observable object with the value to watch.

Prototype¶

^prototype . subscribe ( fn ): Add function to list of callbacks on value change. returns function to used unsubscribe function
^prototype . set ( newValue ): Set the new value to watch. Triggers subscribed functions
^prototype . get ( ): Gets the current watched value.

Example¶

const observable = new Browseth.utils.Observable('123');

const unsubscribe = observable.subscribe(() => console.log('This is an example'));

observable.set('456');  // Sets new value and logs 'This is an example'

unsubscribe(); // unsubscribe earlier subscribed function

observable.set('78'); // Will set new value with no callbacks

observable.get(); // returns '78'

Emitter¶

Add events with callbacks and trigger those callbacks by emitting events.

Creating Instances¶

new ^{Browseth.utils} . Emitter ( ): Create new Emitter object.

Prototype¶

^prototype . on ( event, fn ): Add event label and provide callback
^prototype . off ( event, fn ): Remove callback from an event
^prototype . onEvery ( fn ): Provide callback for every emit
^prototype . emit ( event [, params] ): Emit an event and pass parameters to the callbacks

Example¶

const emitter = new Browseth.utils.Emitter('123');

emitter.on('test', () => console.log('example'));

emitter.onEvery(() => console.log('example2'));

emitter.emit('test') // Console logs 'example' and 'example2'