web3.eth.abi¶
The web3.eth.abi
functions let you de- and encode parameters to ABI (Application Binary Interface) for function calls to the EVM (Ethereum Virtual Machine).
encodeFunctionSignature¶
web3.eth.abi.encodeFunctionSignature(functionName);
Encodes the function name to its ABI signature, which are the first 4 bytes of the sha3 hash of the function name including types.
Parameters¶
1. functionName
- String|Object
: The function name to encode.
or the JSON interface object of the function. If string it has to be in the form function(type,type,...)
, e.g: myFunction(uint256,uint32[],bytes10,bytes)
Returns¶
String
- The ABI signature of the function.
Example¶
// From a JSON interface object
web3.eth.abi.encodeFunctionSignature({
name: 'myMethod',
type: 'function',
inputs: [{
type: 'uint256',
name: 'myNumber'
},{
type: 'string',
name: 'myString'
}]
})
> 0x24ee0097
// Or string
web3.eth.abi.encodeFunctionSignature('myMethod(uint256,string)')
> '0x24ee0097'
encodeEventSignature¶
web3.eth.abi.encodeEventSignature(eventName);
Encodes the event name to its ABI signature, which are the sha3 hash of the event name including input types.
Parameters¶
1. eventName
- String|Object
: The event name to encode.
or the JSON interface object of the event. If string it has to be in the form event(type,type,...)
, e.g: myEvent(uint256,uint32[],bytes10,bytes)
Returns¶
String
- The ABI signature of the event.
Example¶
web3.eth.abi.encodeEventSignature('myEvent(uint256,bytes32)')
> 0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97
// or from a json interface object
web3.eth.abi.encodeEventSignature({
name: 'myEvent',
type: 'event',
inputs: [{
type: 'uint256',
name: 'myNumber'
},{
type: 'bytes32',
name: 'myBytes'
}]
})
> 0xf2eeb729e636a8cb783be044acf6b7b1e2c5863735b60d6daae84c366ee87d97
encodeParameter¶
web3.eth.abi.encodeParameter(type, parameter);
Encodes a parameter based on its type to its ABI representation.
Parameters¶
type
-String|Object
: The type of the parameter, see the solidity documentation for a list of types.parameter
-Mixed
: The actual parameter to encode.
Returns¶
String
- The ABI encoded parameter.
Example¶
web3.eth.abi.encodeParameter('uint256', '2345675643');
> "0x000000000000000000000000000000000000000000000000000000008bd02b7b"
web3.eth.abi.encodeParameter('uint256', '2345675643');
> "0x000000000000000000000000000000000000000000000000000000008bd02b7b"
web3.eth.abi.encodeParameter('bytes32', '0xdf3234');
> "0xdf32340000000000000000000000000000000000000000000000000000000000"
web3.eth.abi.encodeParameter('bytes', '0xdf3234');
> "0x00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000003df32340000000000000000000000000000000000000000000000000000000000"
web3.eth.abi.encodeParameter('bytes32[]', ['0xdf3234', '0xfdfd']);
> "00000000000000000000000000000000000000000000000000000000000000200000000000000000000000000000000000000000000000000000000000000002df32340000000000000000000000000000000000000000000000000000000000fdfd000000000000000000000000000000000000000000000000000000000000"
web3.eth.abi.encodeParameter(
{
"ParentStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256',
"childStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256'
}
}
},
{
"propertyOne": 42,
"propertyTwo": 56,
"childStruct": {
"propertyOne": 45,
"propertyTwo": 78
}
}
);
> "0x000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e"
encodeParameters¶
web3.eth.abi.encodeParameters(typesArray, parameters);
Encodes a function parameters based on its JSON interface object.
Parameters¶
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.
Returns¶
String
- The ABI encoded parameters.
Example¶
web3.eth.abi.encodeParameters(['uint256','string'], ['2345675643', 'Hello!%']);
> "0x000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000"
web3.eth.abi.encodeParameters(['uint8[]','bytes32'], [['34','434'], '0x324567fff']);
> "0x0
web3.eth.abi.encodeParameters(
[
'uint8[]',
{
"ParentStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256',
"ChildStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256'
}
}
}
],
[
['34','434'],
{
"propertyOne": '42',
"propertyTwo": '56',
"ChildStruct": {
"propertyOne": '45',
"propertyTwo": '78'
}
}
]
);
> "0x00000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000018"
encodeFunctionCall¶
web3.eth.abi.encodeFunctionCall(jsonInterface, parameters);
Encodes a function call using its JSON interface object and given paramaters.
Parameters¶
jsonInterface
-Object
: The JSON interface object of a function.parameters
-Array
: The parameters to encode.
Returns¶
String
- The ABI encoded function call. Means function signature + parameters.
Example¶
web3.eth.abi.encodeFunctionCall({
name: 'myMethod',
type: 'function',
inputs: [{
type: 'uint256',
name: 'myNumber'
},{
type: 'string',
name: 'myString'
}]
}, ['2345675643', 'Hello!%']);
> "0x24ee0097000000000000000000000000000000000000000000000000000000008bd02b7b0000000000000000000000000000000000000000000000000000000000000040000000000000000000000000000000000000000000000000000000000000000748656c6c6f212500000000000000000000000000000000000000000000000000"
decodeParameter¶
web3.eth.abi.decodeParameter(type, hexString);
Decodes an ABI encoded parameter to its JavaScript type.
Parameters¶
type
-String|Object
: The type of the parameter, see the solidity documentation for a list of types.hexString
-String
: The ABI byte code to decode.
Returns¶
Mixed
- The decoded parameter.
Example¶
web3.eth.abi.decodeParameter('uint256', '0x0000000000000000000000000000000000000000000000000000000000000010');
> "16"
web3.eth.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000');
> "Hello!%!"
web3.eth.abi.decodeParameter('string', '0x0000000000000000000000000000000000000000000000000000000000000020000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000');
> "Hello!%!"
web3.eth.abi.decodeParameter(
{
"ParentStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256',
"childStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256'
}
}
},
, '0x000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e');
> {
'0': {
'0': '42',
'1': '56',
'2': {
'0': '45',
'1': '78',
'propertyOne': '45',
'propertyTwo': '78'
},
'childStruct': {
'0': '45',
'1': '78',
'propertyOne': '45',
'propertyTwo': '78'
},
'propertyOne': '42',
'propertyTwo': '56'
},
'ParentStruct': {
'0': '42',
'1': '56',
'2': {
'0': '45',
'1': '78',
'propertyOne': '45',
'propertyTwo': '78'
},
'childStruct': {
'0': '45',
'1': '78',
'propertyOne': '45',
'propertyTwo': '78'
},
'propertyOne': '42',
'propertyTwo': '56'
}
}
decodeParameters¶
web3.eth.abi.decodeParameters(typesArray, hexString);
Decodes ABI encoded parameters to its JavaScript types.
Parameters¶
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.
Returns¶
Object
- The result object containing the decoded parameters.
Example¶
web3.eth.abi.decodeParameters(['string', 'uint256'], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000');
> Result { '0': 'Hello!%!', '1': '234' }
web3.eth.abi.decodeParameters([{
type: 'string',
name: 'myString'
},{
type: 'uint256',
name: 'myNumber'
}], '0x000000000000000000000000000000000000000000000000000000000000004000000000000000000000000000000000000000000000000000000000000000ea000000000000000000000000000000000000000000000000000000000000000848656c6c6f212521000000000000000000000000000000000000000000000000');
> Result {
'0': 'Hello!%!',
'1': '234',
myString: 'Hello!%!',
myNumber: '234'
}
web3.eth.abi.decodeParameters([
'uint8[]',
{
"ParentStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256',
"childStruct": {
"propertyOne": 'uint256',
"propertyTwo": 'uint256'
}
}
}
], '0x00000000000000000000000000000000000000000000000000000000000000a0000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000038000000000000000000000000000000000000000000000000000000000000002d000000000000000000000000000000000000000000000000000000000000004e0000000000000000000000000000000000000000000000000000000000000002000000000000000000000000000000000000000000000000000000000000002a0000000000000000000000000000000000000000000000000000000000000018');
> Result {
'0': ['42', '24'],
'1': {
'0': '42',
'1': '56',
'2':
{
'0': '45',
'1': '78',
'propertyOne': '45',
'propertyTwo': '78'
},
'childStruct':
{
'0': '45',
'1': '78',
'propertyOne': '45',
'propertyTwo': '78'
},
'propertyOne': '42',
'propertyTwo': '56'
}
}
decodeLog¶
web3.eth.abi.decodeLog(inputs, hexString, topics);
Decodes ABI encoded log data and indexed topic data.
Parameters¶
inputs
-Object
: A JSON interface inputs array. See the solidity documentation for a list of types.hexString
-String
: The ABI byte code in thedata
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].
Returns¶
Object
- The result object containing the decoded parameters.
Example¶
web3.eth.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'
}