caver.abi

The caver.abi package allows you to decode and encode parameters with an ABI (Application Binary Interface). This will be used for calling functions of a deployed smart contracts.

encodeFunctionSignature

caver.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 parameter types.

Parameters

Name	Type	Description
functionSignature	string | object	The function signature or the JSON interface object of the function to encode. If this is a 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.abi.encodeFunctionSignature({

name: 'myMethod',

type: 'function',

inputs: [{

type: 'uint256',

name: 'myNumber'

},{

type: 'string',

name: 'mystring'

}]

})

'0x24ee0097'

// From a function signature

> caver.abi.encodeFunctionSignature('myMethod(uint256,string)')

'0x24ee0097'

encodeEventSignature

caver.abi.encodeEventSignature(eventSignature)

Encodes the event signature to its ABI signature, which is the sha3 hash of the event name including input parameter types.

Parameters

Name	Type	Description
eventSignature	string | object	The event signature or the JSON interface object of the event to encode. If this is a 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.abi.encodeEventSignature({

name: 'myEvent',

type: 'event',

inputs: [{

type: 'uint256',

name: 'myNumber'

},{

type: 'bytes32',

name: 'myBytes'

}]

})

'0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97'

// From an event signature

> caver.abi.encodeEventSignature('myEvent(uint256,bytes32)')

'0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97'

encodeParameter

caver.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.

NOTE tuple type is supported since caver-js v1.6.0. For more details about tuple type, please refer to Solidity Docs.

Return Value

Type	Description
string	The ABI encoded parameter.

Examples

> caver.abi.encodeParameter('uint256', '2345675643')

'0x000000000000000000000000000000000000000000000000000000008bd02b7b'

> caver.abi.encodeParameter('bytes32', caver.utils.rightPad('0xdf3234', 64))

'0xdf32340000000000000000000000000000000000000000000000000000000000'

> caver.abi.encodeParameter('bytes', '0xdf3234')

'0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000003df32340000000000000000000000000000000000000000000000000000000000'

> caver.abi.encodeParameter('bytes32[]', [caver.utils.rightPad('0xdf3234', 64), caver.utils.rightPad('0xfdfd', 64)])

'0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002df32340000000000000000000000000000000000000000000000000000000000fdfd000000000000000000000000000000000000000000000000000000000000'

> caver.abi.encodeParameter('tuple(bytes32,bool)', ['0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18', true])

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001'

> caver.abi.encodeParameter(

{

components: [{ name: 'a', type: 'bytes32' }, { name: 'b', type: 'bool' }],

name: 'tupleExample',

type: 'tuple',

},

['0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18', true]

)

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001'

encodeParameters

caver.abi.encodeParameters(typesArray, parameters)

Encodes function parameters based on its JSON interface object.

Parameters

Name	Type	Description
typesArray	Array | 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.

NOTE tuple type is supported since caver-js v1.6.0. For more details about tuple type, please refer to Solidity Docs.

Return Value

Type	Description
string	The ABI encoded parameters.

Examples

> caver.abi.encodeParameters(['uint256','string'], ['2345675643', 'Hello!%'])

'0x000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000'

> caver.abi.encodeParameters(['uint8[]','bytes32'], [['34','255'], caver.utils.rightPad('0x324567fff', 64)])

'0x0000000000000000000000000000000000000000000000000000000000000040324567fff00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002200000000000000000000000000000000000000000000000000000000000000ff'

> caver.abi.encodeParameters(

['tuple(bytes32,bool)', 'tuple(bool,address)'],

[

['0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18', true],

[true, '0x77656c636f6d6520746f20657468657265756d2e']

]

)

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000100000000000000000000000077656c636f6d6520746f20657468657265756d2e'

> caver.abi.encodeParameters(

[

{

components: [{ name: 'a', type: 'bytes32' }, { name: 'b', type: 'bool' }],

name: 'tupleExample',

type: 'tuple',

},

{

components: [{ name: 'c', type: 'bool' }, { name: 'd', type: 'address' }],

name: 'tupleExample2',

type: 'tuple',

},

],

[

['0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18', true],

[true, '0x77656c636f6d6520746f20657468657265756d2e']

]

)

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000100000000000000000000000077656c636f6d6520746f20657468657265756d2e'

encodeFunctionCall

caver.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.abi.encodeFunctionCall({

name: 'myMethod',

type: 'function',

inputs: [{

type: 'uint256',

name: 'myNumber'

},{

type: 'string',

name: 'mystring'

}]

}, ['2345675643', 'Hello!%'])

'0x24ee0097000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000'

decodeFunctionCall

caver.abi.decodeFunctionCall(abi, functionCall)

Decodes a function call from its abi object of a function or function abi string and returns parameters.

NOTE caver.abi.decodeFunctionCall is supported since caver-js v1.6.3.

Parameters

Name	Type	Description
abi	object	The abi object of a function.
functionCall	string	The encoded function call string.

Return Value

Type	Description
object	An object which includes plain params. You can use result[0] as it is provided to be accessed like an array in the order of the parameters.

Examples

> caver.abi.decodeFunctionCall({

name: 'myMethod',

type: 'function',

inputs: [{

type: 'uint256',

name: 'myNumber'

},{

type: 'string',

name: 'mystring'

}]

}, '0x24ee0097000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000')

Result {

'0': '2345675643',

'1': 'Hello!%',

__length__: 2,

myNumber: '2345675643',

mystring: 'Hello!%'

}

decodeParameter

caver.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.

NOTE tuple type is supported since caver-js v1.6.0. For more details about tuple type, please refer to Solidity Docs.

Return Value

Type	Description
Mixed	The decoded parameter.

Examples

> caver.abi.decodeParameter('uint256', '0x0000000000000000000000000000000000000000000000000000000000000010')

'16'

> caver.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000')

'Hello!%!'

> caver.abi.decodeParameter('tuple(bytes32,bool)', '0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001')

[ '0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18', true ]

> caver.abi.decodeParameter(

{

components: [{ name: 'a', type: 'bytes32' }, { name: 'b', type: 'bool' }],

name: 'tupleExample',

type: 'tuple',

},

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001'

)

[

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18',

true,

a: '0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18',

b: true

]

decodeParameters

caver.abi.decodeParameters(typesArray, hexstring)

Decodes ABI encoded parameters to its JavaScript types.

Parameters

Name	Type	Description
typesArray	Array | object	An array with types or an array of JSON interface outputs. See the solidity documentation for a list of types.
hexstring	string	The ABI byte code to decode.

NOTE tuple type is supported since caver-js v1.6.0. For more details about tuple type, please refer to Solidity Docs.

Return Value

Type	Description
object	The result object containing the decoded parameters.

Examples

> caver.abi.decodeParameters(['string', 'uint256'], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000')

Result { '0': 'Hello!%!', '1': '234' }

> caver.abi.decodeParameters([{

type: 'string',

name: 'mystring'

},{

type: 'uint256',

name: 'myNumber'

}], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000')

Result {

'0': 'Hello!%!',

'1': '234',

mystring: 'Hello!%!',

myNumber: '234'

}

> caver.abi.decodeParameters(

['tuple(bytes32,bool)', 'tuple(bool,address)'],

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000100000000000000000000000077656c636f6d6520746f20657468657265756d2e'

)

Result {

'0': [ '0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18', true ],

'1': [ true, '0x77656c636f6d6520746F20657468657265756d2E' ],

}

> caver.abi.decodeParameters(

[

{

components: [{ name: 'a', type: 'bytes32' }, { name: 'b', type: 'bool' }],

name: 'tupleExample',

type: 'tuple',

},

{

components: [{ name: 'c', type: 'bool' }, { name: 'd', type: 'address' }],

name: 'tupleExample2',

type: 'tuple',

},

],

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a180000000000000000000000000000000000000000000000000000000000000001000000000000000000000000000000000000000000000000000000000000000100000000000000000000000077656c636f6d6520746f20657468657265756d2e'

)

Result {

'0': [

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18',

true,

a: '0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18',

b: true

],

'1': [

true,

'0x77656c636f6d6520746F20657468657265756d2E',

c: true,

d: '0x77656c636f6d6520746F20657468657265756d2E'

],

tupleExample: [

'0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18',

true,

a: '0xabdef18710a18a18abdef18710a18a18abdef18710a18a18abdef18710a18a18',

b: true

],

tupleExample2: [

true,

'0x77656c636f6d6520746F20657468657265756d2E',

c: true,

d: '0x77656c636f6d6520746F20657468657265756d2E'

]

}

decodeLog

caver.abi.decodeLog(inputs, hexstring, topics)

Decodes ABI encoded log data and indexed topic data.

Parameters

Name	Type	Description
inputs	Array	An array of JSON interface inputs. 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 of the index parameter topics of the log. This array doesn't have topic[0] if it is a non-anonymous event, or otherwise, it has topic[0].

Return Value

Type	Description
object	The result object containing the decoded logs.

Examples

> caver.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'

}

encodeContractDeploy

caver.abi.encodeContractDeploy(jsonInterface, hexstring [, params])

Encodes 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	(optional) 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.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.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.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.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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'