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caver.klay.abi
caver-js APIs related to ABI encoding and decoding.
The caver-klay-abi package allows you to de- and encode parameters from an ABI (Application Binary Interface). This will be used for calling functions of a deployed smart-contract.

caver.klay.abi.encodeFunctionSignature(functionSignature)
Encodes the function signature to its ABI signature, which are the first 4 bytes of the sha3 hash of the function name including types.
Parameters
Name
Type
Description
functionSignature
String | Object
The function signature or the JSON interface object of the function to encode. If String it has to be in the form function(type,type,...), e.g: myFunction(uint256,uint32[],bytes10,bytes)
Return Value
Type
Description
String
The ABI signature of the function.
Examples
// From a JSON interface object
caver.klay.abi.encodeFunctionSignature({
name: 'myMethod',
type: 'function',
inputs: [{
type: 'uint256',
name: 'myNumber'
},{
type: 'string',
name: 'myString'
}]
})
> 0x24ee0097
// From a function signature
caver.klay.abi.encodeFunctionSignature('myMethod(uint256,string)')
> '0x24ee0097'

caver.klay.abi.encodeEventSignature(eventSignature)
Encodes the event signature to its ABI signature, which is the sha3 hash of the event name including input types.
Parameters
Name
Type
Description
eventSignature
String | Object
The event signature or the JSON interface object of the event to encode. If string it has to be in the form event(type,type,...), e.g: myEvent(uint256,uint32[],bytes10,bytes)
Return Value
Type
Description
String
The ABI signature of the event.
Examples
// From a JSON interface object
caver.klay.abi.encodeEventSignature({
name: 'myEvent',
type: 'event',
inputs: [{
type: 'uint256',
name: 'myNumber'
},{
type: 'bytes32',
name: 'myBytes'
}]
})
> 0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97
// From an event signature
caver.klay.abi.encodeEventSignature('myEvent(uint256,bytes32)')
> 0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97

caver.klay.abi.encodeParameter(type, parameter)
Encodes a parameter based on its type to its ABI representation.
Parameters
Name
Type
Description
type
String | Object
The type of the parameter, see the solidity documentation for a list of types.
parameter
Mixed
The actual parameter to encode.
Return Value
Type
Description
String
The ABI encoded parameter.
Examples
caver.klay.abi.encodeParameter('uint256', '2345675643')
> "0x000000000000000000000000000000000000000000000000000000008bd02b7b"
caver.klay.abi.encodeParameter('bytes32', caver.utils.rightPad('0xdf3234', 64))
> "0xdf32340000000000000000000000000000000000000000000000000000000000"
caver.klay.abi.encodeParameter('bytes', '0xdf3234')
> "0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000003df32340000000000000000000000000000000000000000000000000000000000"
caver.klay.abi.encodeParameter('bytes32[]', [caver.utils.rightPad('0xdf3234', 64), caver.utils.rightPad('0xfdfd', 64)])
> "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002df32340000000000000000000000000000000000000000000000000000000000fdfd000000000000000000000000000000000000000000000000000000000000"

caver.klay.abi.encodeParameters(typesArray, parameters)
Encodes function parameters based on its JSON interface object.
Parameters
Name
Type
Description
typesArray
Array<String|Object>|Object
An array with types or a JSON interface of a function. See the solidity documentation for a list of types.
parameters
Array
The parameters to encode.
Return Value
Type
Description
String
The ABI encoded parameters.
Examples
caver.klay.abi.encodeParameters(['uint256','string'], ['2345675643', 'Hello!%'])
> "0x000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000"
caver.klay.abi.encodeParameters(['uint8[]','bytes32'], [['34','255'], caver.utils.rightPad('0x324567fff', 64)])
> "0x0000000000000000000000000000000000000000000000000000000000000040324567fff00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002200000000000000000000000000000000000000000000000000000000000000ff"

caver.klay.abi.encodeFunctionCall(jsonInterface, parameters)
Encodes a function call using its JSON interface object and given parameters.
Parameters
Name
Type
Description
jsonInterface
Object
The JSON interface object of a function.
parameters
Array
The parameters to encode.
Return Value
Type
Description
String
The ABI encoded function call, which means function signature + parameters.
Examples
caver.klay.abi.encodeFunctionCall({
name: 'myMethod',
type: 'function',
inputs: [{
type: 'uint256',
name: 'myNumber'
},{
type: 'string',
name: 'myString'
}]
}, ['2345675643', 'Hello!%'])
> "0x24ee0097000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000"

caver.klay.abi.decodeParameter(type, hexString)
Decodes an ABI encoded parameter to its JavaScript type.
Parameters
Name
Type
Description
type
String|Object
The type of the parameter, see the solidity documentation for a list of types.
hexString
Array
The ABI byte code to decode.
Return Value
Type
Description
Mixed
The decoded parameter.
Examples
caver.klay.abi.decodeParameter('uint256', '0x0000000000000000000000000000000000000000000000000000000000000010')
> "16"
caver.klay.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000')
> "Hello!%!"

caver.klay.abi.decodeParameters(typesArray, hexString)
Decodes ABI encoded parameters to its JavaScript types.
Parameters
Name
Type
Description
typesArray
Array<String|Object>|Object
An array with types or a JSON interface outputs array. See the solidity documentation for a list of types.
hexString
String
The ABI byte code to decode.
Return Value
Type
Description
Object
The result object containing the decoded parameters.
Examples
caver.klay.abi.decodeParameters(['string', 'uint256'], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000')
> Result { '0': 'Hello!%!', '1': '234' }
caver.klay.abi.decodeParameters([{
type: 'string',
name: 'myString'
},{
type: 'uint256',
name: 'myNumber'
}], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000')
> Result {
'0': 'Hello!%!',
'1': '234',
myString: 'Hello!%!',
myNumber: '234'
}

caver.klay.abi.decodeLog(inputs, hexString, topics)
Decodes ABI encoded log data and indexed topic data.
Parameters
Name
Type
Description
inputs
Array
A JSON interface inputs array. See the solidity documentation for a list of types.
hexString
String
The ABI byte code in the data field of a log.
topics
Array
An array with the index parameter topics of the log, without the topic[0] if its a non-anonymous event, otherwise with topic[0].
Return Value
Type
Description
Object
The result object containing the decoded parameters.
Examples
caver.klay.abi.decodeLog([{
type: 'string',
name: 'myString'
},{
type: 'uint256',
name: 'myNumber',
indexed: true
},{
type: 'uint8',
name: 'mySmallNumber',
indexed: true
}],
'0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000748656c6c6f252100000000000000000000000000000000000000000000000000',
['0x000000000000000000000000000000000000000000000000000000000000f310', '0x0000000000000000000000000000000000000000000000000000000000000010'])
> Result {
'0': 'Hello%!',
'1': '62224',
'2': '16',
myString: 'Hello%!',
myNumber: '62224',
mySmallNumber: '16'
}

caver.klay.abi.encodeContractDeploy(jsonInterface, hexString, params)
Encode smart contract bytecode with the arguments of the constructor.
Parameters
Name
Type
Description
jsonInterface
Array
The JSON interface of the contract.
hexString
String
A bytecode of smart contract to be deployed.
params
Mixed
Arguments to pass to the constructor.
Return Value
Type
Description
String
The ABI encoded smart contract deployment with constructor arguments, which means byteCode + parameters.
Examples
// There is no argument for constructor
caver.klay.abi.encodeContractDeploy([
{"constant": true, "inputs": [], "name": "count", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": true, "inputs": [], "name": "getBlockNumber", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": false, "inputs": [ { "name": "_count", "type": "uint256" } ], "name": "setCount", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" }
],'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')
> "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"
// There is one argument for constructor(uint256)
caver.klay.abi.encodeContractDeploy([
{ "constant": true, "inputs": [], "name": "count", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": true, "inputs": [], "name": "getBlockNumber", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": false, "inputs": [ { "name": "_count", "type": "uint256" } ], "name": "setCount", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" },
{ "inputs": [ { "name": "_a", "type": "uint256" } ], "payable": false, "stateMutability": "nonpayable", "type": "constructor" }
],'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', 1)
> "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"
// There are two arguments for constructor(uint256, uint256)
caver.klay.abi.encodeContractDeploy([
{ "constant": true, "inputs": [], "name": "count", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": true, "inputs": [], "name": "getBlockNumber", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": false, "inputs": [ { "name": "_count", "type": "uint256" } ], "name": "setCount", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" },
{ "inputs": [ { "name": "_a", "type": "uint256" }, { "name": "_b", "type": "uint256" } ], "payable": false, "stateMutability": "nonpayable", "type": "constructor" }
],'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', 1, 2)
> "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"
// There is one argument for constructor(string)
caver.klay.abi.encodeContractDeploy([
{ "constant": true, "inputs": [], "name": "count", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": true, "inputs": [], "name": "getBlockNumber", "outputs": [ { "name": "", "type": "uint256" } ], "payable": false, "stateMutability": "view", "type": "function" },
{ "constant": false, "inputs": [ { "name": "_count", "type": "uint256" } ], "name": "setCount", "outputs": [], "payable": false, "stateMutability": "nonpayable", "type": "function" },
{ "inputs": [ { "name": "_a", "type": "string" } ], "payable": false, "stateMutability": "nonpayable", "type": "constructor" }
],'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', 'stringParams')
> "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"
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On this page
encodeFunctionSignature
encodeEventSignature
encodeParameter
encodeParameters
encodeFunctionCall
decodeParameter
decodeParameters
decodeLog
encodeContractDeploy