@appliedblockchain/helpers

Summary

No dependency, single file helpers. Skewed towards ethereum.

Usage

npm i @appliedblockchain/helpers

Api

Table of Contents

• addressOfPrivateKey
  • Parameters
• addressOfPublicKey
  • Parameters
• blockHashOf
  • Parameters
• booleanOfString
  • Parameters
• bufferOfHexOrHex0x
  • Parameters
• defaultCmp
  • Parameters
• eachPromise
  • Parameters
• flagOfBoolean
  • Parameters
  • Examples
• heightOf
  • Parameters
• hex0xOfNumber
  • Parameters
• isLikeDateString
  • Parameters
• isPending
  • Parameters
• isSafeNonNegative
  • Parameters
• isSafePositive
  • Parameters
• makeRetrace
• noop
• randomUint32
• shSync
  • Parameters
• sortedDifference
  • Parameters
• sortedIntersection
  • Parameters
• defaultTimeout
• spread
  • Parameters

addressOfPrivateKey

Parameters

• privateKey Buffer

Returns Buffer ethereum address of provided privateKey.

addressOfPublicKey

Returns ethereum address of provided public key.

Parameters

• publicKey Buffer

Returns Buffer

blockHashOf

Parameters

• url string
• blockNumberOrTag ("earliest" | "latest" | "pending" | number) (optional, default 'latest')
• timeout number (optional, default defaultTiemout)

Returns Promise<string?> block hash as hex0x string or null from provided ethereum jsonrpc endpoint url in specified timeout; null if timeout has been reached.

booleanOfString

Parses string and returns true for "true", "on", "yes" and "1" strings, false otherwise.

Parameters

• value string

Returns boolean

bufferOfHexOrHex0x

Returns Buffer representation of provided hex (ie. "ff") or hex0x (ie. "0xff") string.

Parameters

• value string

• Throws any TypeError On invalid input.

defaultCmp

• See: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/sort#Description

Default comparision function.

Parameters

• x any
• y any

Returns (-1 | 0 | 1)

eachPromise

Similar to Promise.all but yields after each promise settlement. Exceptions are captured and results are yielded as [ err, result, i ] tuple.

Parameters

• promises Array<Promise<T>>

Returns AsyncGenerator<[Error?, T?, number], any, any>

flagOfBoolean

Returns boolean value of command line argument.

Parameters

• name string

Examples

const flagOfBoolean = require('@appliedblockchain/helpers/flag-of-boolean')
console.log(flagOfBoolean('--bar'))
// node foo.js
// false
// node foo.js --bar
// true

heightOf

Parameters

• url string
• timeout number (optional, default defaultTiemout)

Returns Promise<number> Height of the chain from provided ethereum jsonrpc endpoint url or NaN if timeout has been reached or any other problem occured.

hex0xOfNumber

Parameters

• value number

Returns string 0x-prefixed hex string representation of a safe, non-negative integer number.

isLikeDateString

Checks if value looks like YYYY-MM-DD date string.

Parameters

• value any

Returns boolean

isPending

Returns true if promise has not settled yet, false otherwise.

Parameters

• value Promise<any>

Returns boolean

isSafeNonNegative

Returns true if value is safe integer greater than or equal to zero, false otherwise.

Parameters

• value any

Returns boolean

isSafePositive

Parameters

• value number

Returns boolean true if value is safe integer greater than zero, false otherwise.

makeRetrace

Captures extra stack trace, usage await foo().catch(makeRetrace()).

noop

Identity function.

randomUint32

Returns number random unsigned integer that fits 32 bits.

shSync

Executes simple shell command.

Parameters

• cmd string
• $1 any (optional, default {})
  • $1.trim (optional, default true)

sortedDifference

Computes xs - ys difference in linear time between two, unique, ascending arrays of values. Comparision function can be flipped for descending arrays. Leaks values of arrays in thrown error.

Parameters

• xs Array<T>
• ys Array<T>
• cmp function (T, T): (-1 | 0 | 1) (optional, default defaultCmp)

Returns Array<T>

sortedIntersection

Computes intersection in linear time between two, unique, ascending arrays of values. Comparision function can be flipped for descending arrays. Leaks values of arrays in thrown error.

Parameters

• xs Array<T>
• ys Array<T>
• cmp function (T, T): (-1 | 0 | 1) (optional, default defaultCmp)

Returns Array<T>

defaultTimeout

Expire cached nonces after 1 minute.

spread

Spread n calls to f function ms milliseconds apart.

Parameters

• n number
• ms number
• f function (): Promise<any>

Returns Promise<Array<any>>

License

MIT License

Copyright 2019 Applied Blockchain

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.