caver.utils

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caver.utils
caver-js utility APIs.
caver.utils provides utility functions.
randomHex
caver.utils.randomHex(size)
The randomHex library to generate cryptographically strong pseudo-random HEX strings from a given byte size.
Parameters
Name
Type
Description
size
number
The byte size for the HEX string, e.g., 32 will result in a 32-byte HEX string with 64 characters prefixed with "0x".
Return Value
Type
Description
string
The generated random HEX string.
Example
> caver.utils.randomHex(32)
'0x861b56754dba7769f9740c3ad70b4694aa24d604c1dba3bac7ec45978927b8de'
​
> caver.utils.randomHex(4)
'0x5641d6ce'
​
> caver.utils.randomHex(2)
'0xf058'
​
> caver.utils.randomHex(1)
'0x7c'
​
> caver.utils.randomHex(0)
'0x'
_
caver.utils._()
The underscore library for many convenient JavaScript functions.
See the underscore API reference for details.
Example
> var _ = caver.utils._
​
> _.union([1,2],[3])
[1,2,3]
​
> _.each({my: 'object'}, function(value, key){ ... })
...
toBN
caver.utils.toBN(number)
Safely converts any given value (including BigNumber.js instances) into a BN.js instance, for handling big numbers in JavaScript.
Parameters
Name
Type
Description
number
string | number
number to convert to a big number.
Return Value
Type
Description
Object
The BN.js instance.
Examples
> caver.utils.toBN(1234).toString()
'1234'
​
> caver.utils.toBN('1234').add(caver.utils.toBN('1')).toString()
'1235'
​
> caver.utils.toBN('0xea').toString()
'234'
isBN
caver.utils.isBN(bn)
Checks if a given value is a BN.js instance.
Parameters
Name
Type
Description
bn
object
A BN.js instance.
Return Value
Type
Description
boolean
true if a given value is a BN.js instance.
Example
> var number = new caver.utils.BN(10)
> caver.utils.isBN(number)
true
isBigNumber
caver.utils.isBigNumber(bignumber)
Checks if a given value is a BigNumber.js instance.
Parameters
Name
Type
Description
bignumber
object
A BigNumber.js instance.
Return Value
Type
Description
boolean
true if a given value is a BigNumber.js instance.
Example
> var number = new caver.utils.BigNumber(10)
> caver.utils.isBigNumber(number)
true
sha3
caver.utils.sha3(str)
caver.utils.keccak256(str) // ALIAS
Calculates the sha3 of the input.
NOTE: To mimic the sha3 behavior of Solidity use caver.utils.soliditySha3.
Parameters
Name
Type
Description
str
string
A string to hash.
Return Value
Type
Description
string
The result hash.
Example
> caver.utils.sha3('234') // taken as string
'0xc1912fee45d61c87cc5ea59dae311904cd86b84fee17cc96966216f811ce6a79'
​
> caver.utils.sha3(new caver.utils.BN('234')) // utils.sha3 stringify bignumber instance.
'0xc1912fee45d61c87cc5ea59dae311904cd86b84fee17cc96966216f811ce6a79'
​
> caver.utils.sha3(234)
null // can't calculate the has of a number
​
> caver.utils.sha3(0xea) // same as above, just the HEX representation of the number
null
​
> caver.utils.sha3('0xea') // will be converted to a byte array first, and then hashed
'0x2f20677459120677484f7104c76deb6846a2c071f9b3152c103bb12cd54d1a4a'
soliditySha3
caver.utils.soliditySha3(param1 [, param2, ...])
Calculates the sha3 of given input parameters in the same way solidity would. This means arguments will be ABI converted and tightly packed before being hashed.
Parameters
Name
Type
Description
​
​
​
​
​
paramX
Mixed
Any type, or an object with {type: 'uint', value: '123456'} or {t: 'bytes', v: '0xfff456'}. Basic types are autodetected as follows:
 - string non numerical UTF-8 string is interpreted as string.
 - `string
number
BN
HEXpositive number is interpreted asuint256.<br> -string
number
BNnegative number is interpreted asint256.<br> -booleanasbool.<br> -stringHEX string with leading0xis interpreted asbytes.<br> -HEXHEX number representation is interpreted asuint256`.

Return Value
Type
Description
string
The result hash.
Example
> caver.utils.soliditySha3('234564535', '0xfff23243', true, -10)
// auto detects: uint256, bytes, bool, int256
'0x3e27a893dc40ef8a7f0841d96639de2f58a132be5ae466d40087a2cfa83b7179'
​
> caver.utils.soliditySha3('Hello!%') // auto detects: string
'0x661136a4267dba9ccdf6bfddb7c00e714de936674c4bdb065a531cf1cb15c7fc'
​
> caver.utils.soliditySha3('234') // auto detects: uint256
'0x61c831beab28d67d1bb40b5ae1a11e2757fa842f031a2d0bc94a7867bc5d26c2'
​
> caver.utils.soliditySha3(0xea) // same as above
'0x61c831beab28d67d1bb40b5ae1a11e2757fa842f031a2d0bc94a7867bc5d26c2'
​
> caver.utils.soliditySha3(new caver.utils.BN('234')) // same as above
'0x61c831beab28d67d1bb40b5ae1a11e2757fa842f031a2d0bc94a7867bc5d26c2'
​
> caver.utils.soliditySha3({type: 'uint256', value: '234'})) // same as above
'0x61c831beab28d67d1bb40b5ae1a11e2757fa842f031a2d0bc94a7867bc5d26c2'
​
> caver.utils.soliditySha3({t: 'uint', v: new caver.utils.BN('234')})) // same as above
'0x61c831beab28d67d1bb40b5ae1a11e2757fa842f031a2d0bc94a7867bc5d26c2'
​
> caver.utils.soliditySha3('0x407D73d8a49eeb85D32Cf465507dd71d507100c1')
'0x4e8ebbefa452077428f93c9520d3edd60594ff452a29ac7d2ccc11d47f3ab95b'
​
> caver.utils.soliditySha3({t: 'bytes', v: '0x407D73d8a49eeb85D32Cf465507dd71d507100c1'})
'0x4e8ebbefa452077428f93c9520d3edd60594ff452a29ac7d2ccc11d47f3ab95b' // same result as above
​
> caver.utils.soliditySha3({t: 'address', v: '0x407D73d8a49eeb85D32Cf465507dd71d507100c1'})
'0x4e8ebbefa452077428f93c9520d3edd60594ff452a29ac7d2ccc11d47f3ab95b' // same as above, but will do a checksum check, if its multi case
​
> caver.utils.soliditySha3({t: 'bytes32', v: '0x407D73d8a49eeb85D32Cf465507dd71d507100c1'})
'0x3c69a194aaf415ba5d6afca734660d0a3d45acdc05d54cd1ca89a8988e7625b4' // different result as above
​
> caver.utils.soliditySha3({t: 'string', v: 'Hello!%'}, {t: 'int8', v:-23}, {t: 'address', v: '0x85F43D8a49eeB85d32Cf465507DD71d507100C1d'})
'0xa13b31627c1ed7aaded5aecec71baf02fe123797fffd45e662eac8e06fbe4955'
isHex
caver.utils.isHex(hex)
Checks if a given string is a HEX string.
Parameters
Name
Type
Description
hex
string
The given HEX string.
Return Value
Type
Description
boolean
true if a given parameter is a HEX string.
Example
> caver.utils.isHex('0xc1912')
true
​
> caver.utils.isHex('c1912')
true
​
> caver.utils.isHex('0xZ1912')
false
​
> caver.utils.isHex('Hello')
false
isHexStrict
caver.utils.isHexStrict(hex)
Checks if a given string is a HEX string. Difference to caver.utils.isHex is that it expects HEX to be prefixed with 0x.
Parameters
Name
Type
Description
hex
string
The given HEX string.
Return Value
Type
Description
boolean
true if a given string is a HEX string.
Example
> caver.utils.isHexStrict('0xc1912')
true
​
> caver.utils.isHexStrict('c1912')
false
​
> caver.utils.isHexStrict('0xZ1912')
false
​
> caver.utils.isHex('Hello')
false
isAddress
caver.utils.isAddress(address)
Checks if a given string is a valid Klaytn address. It will also check the checksum if the address has upper and lowercase letters.
Parameters
Name
Type
Description
address
string
An address string.
Return Value
Type
Description
boolean
true if a given string is a valid Klaytn address.
Examples
> caver.utils.isAddress('0xc1912fee45d61c87cc5ea59dae31190fffff232d')
true
​
> caver.utils.isAddress('c1912fee45d61c87cc5ea59dae31190fffff232d')
true
​
> caver.utils.isAddress('0XC1912FEE45D61C87CC5EA59DAE31190FFFFF232D')
true // as all is uppercase, no checksum will be checked
​
> caver.utils.isAddress('0xc1912fEE45d61C87Cc5EA59DaE31190FFFFf232d')
true
​
> caver.utils.isAddress('0xC1912fEE45d61C87Cc5EA59DaE31190FFFFf232d')
false // wrong checksum
toChecksumAddress
caver.utils.toChecksumAddress(address)
Converts an upper or lowercase Klaytn address to a checksum address.
Parameters
Name
Type
Description
address
string
An address string.
Return Value
Type
Description
string
The checksum address.
Examples
> caver.utils.toChecksumAddress('0xc1912fee45d61c87cc5ea59dae31190fffff232d')
'0xc1912fEE45d61C87Cc5EA59DaE31190FFFFf232d'
​
> caver.utils.toChecksumAddress('0XC1912FEE45D61C87CC5EA59DAE31190FFFFF232D')
'0xc1912fEE45d61C87Cc5EA59DaE31190FFFFf232d' // same as above
checkAddressChecksum
caver.utils.checkAddressChecksum(address)
Checks the checksum of a given address. Will also return false on non-checksum addresses.
Parameters
Name
Type
Description
address
string
An address string.
Return Value
Type
Description
boolean
true when the checksum of the address is valid, false if it is not a checksum address, or the checksum is invalid.
Examples
> caver.utils.checkAddressChecksum('0xc1912fEE45d61C87Cc5EA59DaE31190FFFFf232d')
true
toHex
caver.utils.toHex(mixed)
Converts any given value to HEX. The numeric strings will be interpreted as numbers. Text strings will be interpreted as UTF-8 strings.
Parameters
Name
Type
Description
mixed
string | number | BN | BigNumber
The input to convert to HEX.
Return Value
Type
Description
string
The resulting HEX string.
Examples
> caver.utils.toHex('234')
'0xea'
​
> caver.utils.toHex(234)
'0xea'
​
> caver.utils.toHex(new caver.utils.BN('234'))
'0xea'
​
> caver.utils.toHex(new caver.utils.BigNumber('234'))
'0xea'
​
> caver.utils.toHex('I have 100€')
'0x49206861766520313030e282ac'
hexToNumberString
caver.utils.hexToNumberString(hex)
Returns the number representation of a given HEX value as a string.
Parameters
Name
Type
Description
hexstring
string
A HEX string to be converted.
Return Value
Type
Description
string
The number as a string.
Examples
> caver.utils.hexToNumberString('0xea')
"234"
hexToNumber
caver.utils.hexToNumber(hex)
Returns the number representation of a given HEX value.
NOTE: This is not useful for big numbers, rather use caver.utils.toBN.
Parameters
Name
Type
Description
hexstring
string
A HEX string to be converted.
Return Value
Type
Description
number
The number representation of a given HEX value.
Examples
> caver.utils.hexToNumber('0xea')
234
numberToHex
caver.utils.numberToHex(number)
Returns the HEX representation of a given number value.
Parameters
Name
Type
Description
number
string | number | BN | BigNumber
A number as string or number.
Return Value
Type
Description
string
The HEX value of the given number.
Examples
> caver.utils.numberToHex('234')
'0xea'
hexToUtf8
caver.utils.hexToUtf8(hex)
caver.utils.hexToString(hex) // ALIAS
Returns the UTF-8 string representation of a given HEX value.
Parameters
Name
Type
Description
hex
string
A HEX string to convert to a UTF-8 string.
Return Value
Type
Description
string
The UTF-8 string.
Examples
> caver.utils.hexToUtf8('0x49206861766520313030e282ac')
'I have 100€'
hexToAscii
caver.utils.hexToAscii(hex)
Returns the ASCII string representation of a given HEX value.
Parameters
Name
Type
Description
hex
string
A HEX string to convert to an ASCII string.
Return Value
Type
Description
string
The ASCII string.
Examples
> caver.utils.hexToAscii('0x4920686176652031303021')
'I have 100!'
utf8ToHex
caver.utils.utf8ToHex(str)
caver.utils.stringToHex(str) // ALIAS
Returns the HEX representation of a given UTF-8 string.
Parameters
Name
Type
Description
str
string
A UTF-8 string to convert to a HEX string.
Return Value
Type
Description
string
The HEX string.
Examples
> caver.utils.utf8ToHex('I have 100€')
'0x49206861766520313030e282ac'
asciiToHex
caver.utils.asciiToHex(str)
Returns the HEX representation of a given ASCII string.
Parameters
Name
Type
Description
str
string
An ASCII string to convert to a HEX string.
Return Value
Type
Description
string
The HEX string.
Examples
> caver.utils.asciiToHex('I have 100!')
'0x4920686176652031303021'
hexToBytes
caver.utils.hexToBytes(hex)
Returns a byte array from the given HEX string.
Parameters
Name
Type
Description
hex
string
A HEX string to be converted.
Return Value
Type
Description
Array
The byte array.
Examples
> caver.utils.hexToBytes('0x000000ea')
[ 0, 0, 0, 234 ]
bytesToHex
caver.utils.bytesToHex(byteArray)
Returns a HEX string from a byte array.
Parameters
Name
Type
Description
byteArray
Array
A byte array to convert.
Return Value
Type
Description
string
The HEX string.
Examples
> caver.utils.bytesToHex([ 72, 101, 108, 108, 111, 33, 36 ])
'0x48656c6c6f2124'
convertToPeb
caver.utils.convertToPeb(number [, unit])
Converts any KLAY value into peb.
NOTE: "peb" is the smallest KLAY unit, and you should always use "peb" as the unit of KLAY. Convert to "KLAY" only for display reasons.
Parameters
Name
Type
Description
number
string | number | BN
The value.
unit
string
(optional, defaults to "KLAY") The unit of KLAY to convert from. number will be multiplied by one of the following multipliers for the unit provided:
- peb: '1' 
 - kpeb: '1000' 
 - Mpeb: '1000000' 
 - Gpeb: '1000000000' 
 - Ston: '1000000000' 
 - uKLAY: '1000000000000' 
 - mKLAY: '1000000000000000' 
 - KLAY: '1000000000000000000' 
 - kKLAY: '1000000000000000000000' 
 - MKLAY: '1000000000000000000000000' 
 - GKLAY: '1000000000000000000000000000' 

Return Value
Type
Description
string | BN
If the number parameter is an instance of BN, it returns a BN instance, otherwise a string.
Examples
> caver.utils.convertToPeb('1', 'KLAY')
'1000000000000000000'
​
> caver.utils.convertToPeb(caver.utils.toBN(1), 'KLAY')
<BN: de0b6b3a7640000>
convertFromPeb
caver.utils.convertFromPeb(number [, unit])
NOTE: "peb" is the smallest KLAY unit, and you should always use "peb" as the unit of KLAY. Convert to "KLAY" only for display reasons.
Parameters
Name
Type
Description
number
string | number | BN | BigNumber
The value in peb.
unit
string
(optional, defaults to "KLAY") The unit of KLAY to convert your "peb" into. number will be divided by one of the following denominators for the unit provided:
- peb: '1' 
 - kpeb: '1000' 
 - Mpeb: '1000000' 
 - Gpeb: '1000000000' 
 - Ston: '1000000000' 
 - uKLAY: '1000000000000' 
 - mKLAY: '1000000000000000' 
 - KLAY: '1000000000000000000' 
 - kKLAY: '1000000000000000000000' 
 - MKLAY: '1000000000000000000000000' 
 - GKLAY: '1000000000000000000000000000' 

Return Value
Type
Description
string
The string number.
Examples
> caver.utils.convertFromPeb('1', 'KLAY')
'0.000000000000000001'
unitMap
caver.utils.unitMap
Shows all possible KLAY values and their amount in peb.
Return Value
Type
Description
Object
With the following properties:
- peb: '1' 
 - kpeb: '1000' 
 - Mpeb: '1000000' 
 - Gpeb: '1000000000' 
 - Ston: '1000000000' 
 - uKLAY: '1000000000000' 
 - mKLAY: '1000000000000000' 
 - KLAY: '1000000000000000000' 
 - kKLAY: '1000000000000000000000' 
 - MKLAY: '1000000000000000000000000' 
 - GKLAY: '1000000000000000000000000000' 
 - TKLAY: '1000000000000000000000000000000' 

Examples
> caver.utils.unitMap
{
  peb: '1',
  kpeb: '1000',
  Mpeb: '1000000',
  Gpeb: '1000000000',
  Ston: '1000000000',
  uKLAY: '1000000000000',
  mKLAY: '1000000000000000',
  KLAY: '1000000000000000000',
  kKLAY: '1000000000000000000000',
  MKLAY: '1000000000000000000000000',
  GKLAY: '1000000000000000000000000000',
  TKLAY: '1000000000000000000000000000000'
}
klayUnit
caver.utils.klayUnit
Shows all KLAY units.
Return Value
Type
Description
Object
An object in which the units of KLAY used in Klaytn are defined. Each unit has its name and pebFactor. pebFactor is used when converting KLAY currently translated in each unit to 'peb'.
Examples
> caver.utils.klayUnit
{
    peb: { unit: 'peb', pebFactor: 0 },
    kpeb: { unit: 'kpeb', pebFactor: 3 },
    Mpeb: { unit: 'Mpeb', pebFactor: 6 },
    Gpeb: { unit: 'Gpeb', pebFactor: 9 },
    ston: { unit: 'ston', pebFactor: 9 },
    uKLAY: { unit: 'uKLAY', pebFactor: 12 },
    mKLAY: { unit: 'mKLAY', pebFactor: 15 },
    KLAY: { unit: 'KLAY', pebFactor: 18 },
    kKLAY: { unit: 'kKLAY', pebFactor: 21 },
    MKLAY: { unit: 'MKLAY', pebFactor: 24 },
    GKLAY: { unit: 'GKLAY', pebFactor: 27 },
    TKLAY: { unit: 'TKLAY', pebFactor: 30 }
}
padLeft
caver.utils.padLeft(string, characterAmount [, sign])
caver.utils.leftPad(string, characterAmount [, sign]) // ALIAS
Adds padding on the left of a string. Useful for adding paddings to HEX strings.
Parameters
Name
Type
Description
string
string
The string to add padding on the left.
characterAmount
number
The number of characters the total string should have.
sign
string
(optional) The character sign to use, defaults to 0.
Return Value
Type
Description
string
The padded string.
Examples
> caver.utils.padLeft('0x3456ff', 20)
'0x000000000000003456ff'
​
> caver.utils.padLeft(0x3456ff, 20)
'0x000000000000003456ff'
​
> caver.utils.padLeft('Hello', 20, 'x')
'xxxxxxxxxxxxxxxHello'
padRight
caver.utils.padRight(str, characterAmount [, sign])
caver.utils.rightPad(str, characterAmount [, sign]) // ALIAS
Adds padding on the right of a string, Useful for adding paddings to HEX strings.
Parameters
Name
Type
Description
str
string
The string to add padding on the right.
characterAmount
number
The number of characters the total string should have.
sign
string
(optional) The character sign to use, defaults to 0.
Return Value
Type
Description
string
The padded string.
Examples
> caver.utils.padRight('0x3456ff', 20)
'0x3456ff00000000000000'
​
> caver.utils.padRight(0x3456ff, 20)
'0x3456ff00000000000000'
​
> caver.utils.padRight('Hello', 20, 'x')
'Helloxxxxxxxxxxxxxxx'
trimLeadingZero
caver.utils.trimLeadingZero(hexString)
Removes leading zero from 0x-prefixed hex string.
Parameters
Name
Type
Description
hexString
string