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 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 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 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 BN('234')) // same as above
'0x61c831beab28d67d1bb40b5ae1a11e2757fa842f031a2d0bc94a7867bc5d26c2'
​
> caver.utils.soliditySha3({type: 'uint256', value: '234'})) // same as above
'0x61c831beab28d67d1bb40b5ae1a11e2757fa842f031a2d0bc94a7867bc5d26c2'
​
> caver.utils.soliditySha3({t: 'uint', v: new 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 BN('234'))
'0xea'
​
> caver.utils.toHex(new 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
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'
toTwosComplement
caver.utils.toTwosComplement(num)
Converts a negative number into a two's complement.
Parameters
Name
Type
Description
num
number | string | Bignumber
The number to convert.
Return Value
Type
Description
string
The converted hex string.
Examples
> caver.utils.toTwosComplement('-1')
'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff'
​
> caver.utils.toTwosComplement(-1)
'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff'
​
> caver.utils.toTwosComplement('0x1')
'0x0000000000000000000000000000000000000000000000000000000000000001'
​
> caver.utils.toTwosComplement(-15)
'0xfffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff1'
​
> caver.utils.toTwosComplement('-0x1')
'0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff'
isContractDeployment
caver.utils.isContractDeployment(transactionObject)
Returns true if the given transaction is a smart contract deploy transaction. It returns false if the transaction is not a smart contract deploy transaction. The result is determined by the values of the parameters in the transactionObject. Make sure all the mandatory parameters are set correctly.
Parameters
Name
Type
Description
transactionObject
object
An instance of Transaction to check contract deploy transaction or not.
Return Value
Type
Description
boolean
true means the transaction object is for smart contract deploy.
Examples
> caver.utils.isContractDeployment(caver.transaction.legacyTransaction.create({
    to: '0x9957dfd92e4b70f91131c573293343bc5f21f215',
    value: caver.utils.toPeb(1, 'KLAY'),
    gas: 25000,
}))
false
​
> caver.utils.isContractDeployment(caver.transaction.legacyTransaction.create({
    input: '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',
    gas: 200000,
}))
true
​
> caver.utils.isContractDeployment(caver.transaction.smartContractDeploy.create({
    from: '0x88e245dec96830f012f8fc1806bc623b3774560d',
    input: '0x608060405234801561001057600080fd5b506101de806100206000396000f3006080604052600436106100615763ffffffff7c01000000000000000000000000000000000000000000000000000000006000350416631a39d8ef81146100805780636353586b146100a757806370a08231146100ca578063fd6b7ef8146100f8575b3360009081526001602052604081208054349081019091558154019055005b34801561008c57600080fd5b5061009561010d565b60408051918252519081900360200190f35b6100c873ffffffffffffffffffffffffffffffffffffffff60043516610113565b005b3480156100d657600080fd5b5061009573ffffffffffffffffffffffffffffffffffffffff60043516610147565b34801561010457600080fd5b506100c8610159565b60005481565b73ffffffffffffffffffffffffffffffffffffffff1660009081526001602052604081208054349081019091558154019055565b60016020526000908152604090205481565b336000908152600160205260408120805490829055908111156101af57604051339082156108fc029083906000818181858888f193505050501561019c576101af565b3360009081526001602052604090208190555b505600a165627a7a72305820627ca46bb09478a015762806cc00c431230501118c7c26c30ac58c4e09e51c4f0029',
    gas: 100000,
}))
true
​
> caver.utils.isContractDeployment(caver.transaction.feeDelegatedSmartContractDeploy.create({
    from: '0x88e245dec96830f012f8fc1806bc623b3774560d',
    input: '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',
    gas: 100000,
}))
true
​
> caver.utils.isContractDeployment(caver.transaction.feeDelegatedSmartContractDeployWithRatio.create({
    from: '0x88e245dec96830f012f8fc1806bc623b3774560d',
    input: '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',
    gas: 100000,
    feeRatio: 30,
}))
true
xyPointFromPublicKey
caver.utils.xyPointFromPublicKey(publicKey)
Returns the x and y coordinates of the given publicKey. For more information on key cryptography, see Elliptic-curve cryptography.
NOTE This function does not contain any logic to check whether the public key is valid. The function only split the input publicKey into x and y points by length. To validate public key, please use isValidPublicKey.
Parameters
Name
Type
Description
publicKey
string
The publicKey to get x and y points.
Return Value
Type
Description
Array
An array storing x and y points. Index 0 has x point, and index 1 has y point.
Examples
> caver.utils.xyPointFromPublicKey('0xa5862ded55cd9c7e9ff246dbc264ca5d5c605308f59b74e581b4f089d4c8c88cb9f00df6a56493f6029af215d266c907660ea0f7a4111ea025ea9d9be418fa55')
[ 
    '0xa5862ded55cd9c7e9ff246dbc264ca5d5c605308f59b74e581b4f089d4c8c88c',
    '0xb9f00df6a56493f6029af215d266c907660ea0f7a4111ea025ea9d9be418fa55'
]
isHexPrefixed
caver.utils.isHexPrefixed(input)
Returns true if the input is a 0x-prefixed hex string, otherwise it returns false.
Parameters
Name
Type
Description
input
string
The value to be determined if the parameter is 0x-prefixed hex string or not.
Return Value
Type
Description
boolean
true means the input is 0x-prefixed hex string.
Examples
> caver.utils.isHexPrefixed('0xa5b0cd8c87e77879d64cc064ee239ed6f71cacf9')
true
​
> caver.utils.isHexPrefixed('0x1')
true
​
> caver.utils.isHexPrefixed('0xqwer')
false
​
> caver.utils.isHexPrefixed('1')
false
addHexPrefix
caver.utils.addHexPrefix(input)
Returns a 0x-prefixed hex string. If the input is already 0x-prefixed or a non-hex string, the input value is returned as-is.
Parameters
Name
Type
Description
input
string
string value to be prefixed with 0x.
Return Value
Type
Description
string
0x-prefixed hex string is returned.
Examples
> caver.utils.addHexPrefix('a5b0cd8c87e77879d64cc064ee239ed6f71cacf9')
'0xa5b0cd8c87e77879d64cc064ee239ed6f71cacf9'
​
> caver.utils.addHexPrefix('0xa5b0cd8c87e77879d64cc064ee239ed6f71cacf9')
'0xa5b0cd8c87e77879d64cc064ee239ed6f71cacf9'
stripHexPrefix
caver.utils.stripHexPrefix(input)
Returns the result with 0x prefix stripped from input.
NOTE caver.klay.stripHexPrefix is supported from v1.0.1. To use this feature, please install v1.0.1 or higher.
Parameters
Name
Type
Description
input
string
string to remove 0x prefix.
Return Value
Type
Description
string
A string stripped of 0x is returned.
Examples
> caver.utils.stripHexPrefix('a5b0cd8c87e77879d64cc064ee239ed6f71cacf9')
'a5b0cd8c87e77879d64cc064ee239ed6f71cacf9'
​
> caver.utils.stripHexPrefix('0xa5b0cd8c87e77879d64cc064ee239ed6f71cacf9')
'a5b0cd8c87e77879d64cc064ee239ed6f71cacf9'
toBuffer
caver.utils.toBuffer(input)
This function converts the input to a Buffer. To convert an object into a Buffer using toBuffer, the object must implement toArray function. For string type input, this function only works with a 0x-prefixed hex string.
Parameters
Name
Type
Description
input
Buffer | string | number | Array | BN | object
The value to be converted to a Buffer.
Return Value
Type
Description
Buffer
The value converted to Buffer type is returned.
Examples
// Buffer
> caver.utils.toBuffer(Buffer.alloc(0))
<Buffer >
​
// 0x-prefixed hex string
> caver.utils.toBuffer('0x1234')
<Buffer 12 34>
​
// number
> caver.utils.toBuffer(1)
<Buffer 01>
​
// Array
> caver.utils.toBuffer([1,2,3])
<Buffer 01 02 03>
​
// BN
> caver.utils.toBuffer(new caver.utils.BN(255))
<Buffer ff>
​
// Object that implements toArray function
> caver.utils.toBuffer({toArray: function() {return [1,2,3,4]}})
<Buffer 01 02 03 04>
​
// null or undefined
> caver.utils.toBuffer(null)
<Buffer >
​
> caver.utils.toBuffer(undefined)
<Buffer >
​
// non 0x-prefixed hex string
> caver.utils.toBuffer('0xqwer')
Error: Failed to convert string to Buffer. 'toBuffer' function only supports 0x-prefixed hex string
​
// Object that does not implement toArray function
> caver.utils.toBuffer({})
Error: To convert an object to a buffer, the toArray function must be implemented inside the object
numberToBuffer
caver.utils.numberToBuffer(input)
This function converts a number to a Buffer. The caver.utils.toBuffer has the same behavior as this function when the input is a number.
Parameters
Name
Type
Description
input
string | number | BN
A number to be converted to a Buffer.
Return Value
Type
Description
Buffer
The value converted to Buffer type is returned.
Examples
> caver.utils.numberToBuffer(1)
<Buffer 01>
​
> caver.utils.numberToBuffer('2')
<Buffer 02>
​
> caver.utils.numberToBuffer('0x3')
<Buffer 03>
​
> caver.utils.numberToBuffer(new caver.utils.BN(4))
<Buffer 04>
isValidHash
caver.utils.isValidHash(input)
Returns true if the input is in 32-bytes hash format, otherwise it returns false.
Parameters
Name
Type
Description
input
string
The value to be examined that if it is in 32-bytes hash format or not.
Return Value
Type
Description
boolean
true means the input is in the format of 32-bytes hash.
Examples
// with '0x' hex prefix
> caver.utils.isValidHash('0xe9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
true
​
// without '0x' hex prefix
> caver.utils.isValidHash('e9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
true
​
> caver.utils.isValidHash('0x1')
false
isValidHashStrict
caver.utils.isValidHashStrict(input)
Returns true if the input is in 0x-prefixed 32-bytes hash format, otherwise it returns false. This function only looks at the input and determines if it is in the format of 0x-prefixed 32-bytes hash. Difference to caver.utils.isValidHash is that it expects HEX to be prefixed with 0x.
Parameters
Name
Type
Description
input
string
The value to be examined that if it is in the format of 0x-prefixed 32-bytes hash or not.
Return Value
Type
Description
boolean
true means the input is in the format of 0x-prefixed 32-bytes hash.
Examples
// with '0x' hex prefix
> caver.utils.isValidHashStrict('0xe9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
true
​
// without '0x' hex prefix
> caver.utils.isValidHashStrict('e9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
false
​
> caver.utils.isValidHashStrict('0x1')
false
isTxHash
caver.utils.isTxHash(input)
Returns true if the input is in transaction hash format, otherwise it returns false. This function only looks at the input and determines if it is in the format of a transaction hash.
NOTE This function has been deprecated. Use isValidHash to determine if a valid hash is 32 bytes long.
Parameters
Name
Type
Description
input
string
The value to be determined if the parameter is in the format of transaction hash or not.
Return Value
Type
Description
boolean
true means the input is in the format of transaction hash.
Examples
// with '0x' hex prefix
> caver.utils.isTxHash('0xe9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
true
​
// without '0x' hex prefix
> caver.utils.isTxHash('e9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
true
​
> caver.utils.isTxHash('0x1')
false
isTxHashStrict
caver.utils.isTxHashStrict(input)
Returns true if the input is in transaction hash format, otherwise it returns false. This function only looks at the input and determines if it is in the format of a transaction hash. Difference to caver.utils.isTxHash is that it expects HEX to be prefixed with 0x.
NOTE This function has been deprecated. Use isValidHashStrict to determine if a valid hash is 32 bytes long.
Parameters
Name
Type
Description
input
string
The value to be determined if the parameter is in the format of transaction hash or not.
Return Value
Type
Description
boolean
true means the input is in the format of transaction hash.
Examples
// with '0x' hex prefix
> caver.utils.isTxHashStrict('0xe9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
true
​
// without '0x' hex prefix
> caver.utils.isTxHashStrict('e9a11d9ef95fb437f75d07ce768d43e74f158dd54b106e7d3746ce29d545b550')
false
​
> caver.utils.isTxHashStrict('0x1')
false
isValidPrivateKey
caver.utils.isValidPrivateKey(privateKey)
Returns true if privateKey is valid, otherwise it returns false.
Parameters
Name
Type
Description
privateKey
string
A private key string to validate.
Return Value
Type
Description
boolean
true means the privateKey is valid.
Examples
> caver.utils.isValidPrivateKey('0x{private key}')
true
​
> caver.utils.isValidPrivateKey('{private key}')
true
​
> caver.utils.isValidPrivateKey('a5b0cd8c87e77879d64cc064ee239ed6f71cacf9')
false
isValidPublicKey
caver.utils.isValidPublicKey(publicKey)
Returns true if publicKey is valid, otherwise it returns false.
Parameters
Name
Type
Description
publicKey
string
A public key string to validate.
Return Value
Type
Description
boolean
true means the publicKey is valid.
Examples
// validation with uncompressed public key
> caver.utils.isValidPublicKey('0xbd6405a7f14f57ecea4a6ffe774ee26d051f7eed13257c9a574055b20e42bab0e8beba92e2e675101eb2a55ba4693080d0bf14548beae7bc93b18b72d10dd350')
true
​
// validation with compressed public key
> caver.utils.isValidPublicKey('0x02bd6405a7f14f57ecea4a6ffe774ee26d051f7eed13257c9a574055b20e42bab0')
true
​
> caver.utils.isValidPublicKey('{private key}')
false
​
> caver.utils.isValidPublicKey('0x{private key}')
false
​
> caver.utils.isValidPublicKey('a5b0cd8c87e77879d64cc064ee239ed6f71cacf9')
false
isValidRole
caver.utils.isValidRole(role)
Returns true if a role is valid, otherwise it returns false. You can check roles supported by caver-js through caver.wallet.keyring.role.
Parameters
Name
Type
Description
role
string
A role string to validate.
Return Value
Type
Description
boolean
true means the role is valid.
Examples
> caver.utils.isValidRole('roleTransactionKey')
true
​
> caver.utils.isValidRole('role')
false
isEmptySig
caver.utils.isEmptySig(sig)
Returns true if sig is in the format of empty signature (SignatureData { _v: '0x01', _r: '0x', _s: '0x' } or [SignatureData { _v: '0x01', _r: '0x', _s: '0x' }]), otherwise it returns false.
In caver-js, if signatures or feePayerSignatures is empty, the value representing an empty signature, [SignatureData { _v: '0x01', _r: '0x', _s: '0x' }], is returned for the property. This function is used to check whether the given signature is [SignatureData { _v: '0x01', _r: '0x', _s: '0x' }] (or SignatureData { _v: '0x01', _r: '0x', _s: '0x' } in the 'LEGACY' transaction).
Parameters
Name
Type
Description
sig
object | Array
An instance of SignatureData or array of SignatureData to check empty or not.
Return Value
Type
Description
boolean
true means the sig is empty.
Examples
> caver.utils.isEmptySig(caver.wallet.keyring.signatureData.emtpySig)
true
​
> caver.utils.isEmptySig([caver.wallet.keyring.signatureData.emtpySig])
true
isKlaytnWalletKey
caver.utils.isKlaytnWalletKey(key)
Returns true if key is in KlaytnWalletKey format, otherwise it returns false.
Parameters
Name
Type
Description
key
string
A key string to check in the format of KlaytnWalletKey or not.
Return Value
Type
Description
boolean
true means the key is 0x{private key}0x{type}0x{address in hex} or {private key}0x{type}0x{address in hex}.
Examples
> caver.utils.isKlaytnWalletKey('0x{private key}0x{type}0x{address in hex}')
true
​
> caver.utils.isKlaytnWalletKey('{private key}0x{type}0x{address in hex}')
true
​
> caver.utils.isKlaytnWalletKey('0x{private key}')
false
bufferToHex
caver.utils.bufferToHex(buffer)
Converts buffer to 0x-prefixed hex string.
Parameters
Name
Type
Description
buffer
Buffer
A buffer to convert to hex string.
Return Value
Type
Description
string
The 0x-prefixed hex string.
Examples
> caver.utils.bufferToHex(Buffer.from('5b9ac8', 'hex'))
'0x5b9ac8'
​
> caver.utils.bufferToHex(Buffer.alloc(0))
'0x'
parseKlaytnWalletKey
caver.utils.parseKlaytnWalletKey(key)
Parses KlaytnWalletKey string to an array which includes "private key", "type", "address".
Parameters
Name
Type
Description
key
string
A KlaytnWalletKey string.
Return Value
Type
Description
Array
The parsed KlaytnWalletKey.
Examples
> caver.utils.parseKlaytnWalletKey('0x{private key}0x{type}0x{address in hex}')
[
    '0x{private key}',
    '0x00',
    '0x885ebdb17c221ef695936b18a0263d6399e14d60'
]
hashMessage
caver.utils.hashMessage(message)
Hashes message with Klaytn specific prefix: keccak256("\x19Klaytn Signed Message:\n" + len(message) + message))
Parameters
Name
Type
Description
message
string
A message to hash. If it is a HEX string, it will be UTF-8 decoded first.
Return Value
Type
Description
string
The hashed message with Klaytn specific prefix.
Examples
> caver.utils.hashMessage('Hello')
'0x640bfab59b6e27468abd367888f4ab1a1c77aa2b45e76a1d3adcbd039c305917'
recover
caver.utils.recover(message, signature [, preFixed])
Recovers the Klaytn address that was used to sign the given data.
Parameters
Name
Type
Description
message
string
Either message or hashed message.
signature
object
An instance of SignatureData.
preFixed
boolean
(optional, default: false) If the last parameter is true, the given message will NOT automatically be prefixed with "\x19Klaytn Signed Message:\n" + message.length + message, and be assumed as already prefixed.
Return Value
Type
Description
string
The Klaytn address used to sign this data.
Examples
> const sig = new caver.wallet.keyring.signatureData(['0x1b', '0x50a80...', '0x021de...'])
​
> caver.utils.recover('message', sig)
'0xe8b3a6ef12f9506e1df9fd445f9bb4488a482122'
​
> caver.utils.recover('0xe960248437f2134a77a9aa0ebcbb6523aec095f23b02e25f16fd95e99b099daa', sig, true)
'0xe8b3a6ef12f9506e1df9fd445f9bb4488a482122'
compressPublicKey
caver.utils.compressPublicKey(uncompressedPublicKey)
Compresses the uncompressed public key.
Parameters
Name
Type
Description
uncompressedPublicKey
string
An uncompressed public key.
Return Value
Type
Description
string
A compressed public key.
Examples
> caver.<
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".
Type	Description
boolean	`true` if a given value is a BN.js instance.
Type	Description
string \| BN	If the number parameter is an instance of BN, it returns a BN instance, otherwise a string.
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'
Type	Description
Array	An array storing x and y points. Index 0 has x point, and index 1 has y point.
Type	Description
Buffer	The value converted to Buffer type is returned.
Type	Description
string	The hashed message with Klaytn specific prefix.