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'

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" }
],'0x60806040526000805534801561001457600080fd5b50610116806100246000396000f3006080604052600436106053576000357c0100000000000000000000000000000000000000000000000000000000900463ffffffff16806306661abd14605857806342cbb15c146080578063d14e62b81460a8575b600080fd5b348015606357600080fd5b50606a60d2565b6040518082815260200191505060405180910390f35b348015608b57600080fd5b50609260d8565b6040518082815260200191505060405180910390f35b34801560b357600080fd5b5060d06004803603810190808035906020019092919050505060e0565b005b60005481565b600043905090565b80600081905550505600a165627a7a7230582064856de85a2706463526593b08dd790054536042ef66d3204018e6790a2208d10029')
'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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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'