Note

This documentation is work in progress and web3.js 1.0 is not yet released! You can find the current documentation for web3 0.x.x at github.com/ethereum/wiki/wiki/JavaScript-API.

web3.eth.Contract

The web3.eth.Contract object makes it easy to interact with smart contracts on the ethereum blockchain. When you create a new contract object you give it the json interface of the respective smart contract and web3 will auto convert all calls into low level ABI calls over RPC for you.

This allows you to interact with smart contracts as if they were JavaScript objects.

To use it standalone:


new contract

new web3.eth.Contract(jsonInterface[, address][, options])

Creates a new contract instance with all its methods and events defined in its json interface object.

Parameters

  1. jsonInterface - Object: The json interface for the contract to instantiate
  2. address - String (optional): The address of the smart contract to call, can be added later using myContract.options.address = '0x1234..'
  3. options - Object (optional): The options of the contract. Some are used as fallbacks for calls and transactions:
    • from - String: The address transactions should be made from.
    • gasPrice - String: The gas price in wei to use for transactions.
    • gas - Number: The maximum gas provided for a transaction (gas limit).
    • data - String: The byte code of the contract. Used when the contract gets deployed.

Returns

Object: The contract instance with all its methods and events.

Example

var myContract = new web3.eth.Contract([...], '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe', {
    from: '0x1234567890123456789012345678901234567891', // default from address
    gasPrice: '20000000000' // default gas price in wei, 20 gwei in this case
});

= Properties =


options

myContract.options

The options object for the contract instance. from, gas and gasPrice are used as fallback values when sending transactions.

Properties

Object - options:

  • address - String: The address where the contract is deployed. See options.address.
  • jsonInterface - Array: The json interface of the contract. See options.jsonInterface.
  • data - String: The byte code of the contract. Used when the contract gets deployed.
  • from - String: The address transactions should be made from.
  • gasPrice - String: The gas price in wei to use for transactions.
  • gas - Number: The maximum gas provided for a transaction (gas limit).

Example

myContract.options;
> {
    address: '0x1234567890123456789012345678901234567891',
    jsonInterface: [...],
    from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe',
    gasPrice: '10000000000000',
    gas: 1000000
}

myContract.options.from = '0x1234567890123456789012345678901234567891'; // default from address
myContract.options.gasPrice = '20000000000000'; // default gas price in wei
myContract.options.gas = 5000000; // provide as fallback always 5M gas

options.address

myContract.options.address

The address used for this contract instance. All transactions generated by web3.js from this contract will contain this address as the “to”.

The address will be stored in lowercase.

Property

address - String|null: The address for this contract, or null if it’s not yet set.

Example

myContract.options.address;
> '0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae'

// set a new address
myContract.options.address = '0x1234FFDD...';

options.jsonInterface

myContract.options.jsonInterface

The json interface object derived from the ABI of this contract.

Property

jsonInterface - Array: The json interface for this contract. Re-setting this will regenerate the methods and events of the contract instance.

Example

myContract.options.jsonInterface;
> [{
    "type":"function",
    "name":"foo",
    "inputs": [{"name":"a","type":"uint256"}],
    "outputs": [{"name":"b","type":"address"}]
},{
    "type":"event",
    "name":"Event"
    "inputs": [{"name":"a","type":"uint256","indexed":true},{"name":"b","type":"bytes32","indexed":false}],
}]

// set a new interface
myContract.options.jsonInterface = [...];

= Methods =


clone

myContract.clone()

Clones the current contract instance.

Parameters

none

Returns

Object: The new contract instance.

Example

var contract1 = new eth.Contract(abi, address, {gasPrice: '12345678', from: fromAddress});

var contract2 = contract1.clone();
contract2.options.address = address2;

(contract1.options.address !== contract2.options.address);
> true

deploy

myContract.deploy(options)

Call this function to deploy the contract to the blockchain. After successful deployment the promise will resolve with a new contract instance.

Parameters

  1. options - Object: The options used for deployment.
    • data - String: The byte code of the contract.
    • arguments - Array (optional): The arguments which get passed to the constructor on deployment.

Returns

Object: The transaction object:

  • Array - arguments: The arguments passed to the method before. They can be changed.
  • Function - send: Will deploy the contract. The promise will resolve with the new contract instance, instead of the receipt!
  • Function - estimateGas: Will estimate the gas used for deploying.
  • Function - encodeABI: Encodes the ABI of the deployment, which is contract data + constructor parameters
For details to the methods see the documentation below.

Example

myContract.deploy({
    data: '0x12345...',
    arguments: [123, 'My String']
})
.send({
    from: '0x1234567890123456789012345678901234567891',
    gas: 1500000,
    gasPrice: '30000000000000'
}, function(error, transactionHash){ ... })
.on('error', function(error){ ... })
.on('transactionHash', function(transactionHash){ ... })
.on('receipt', function(receipt){
   console.log(receipt.contractAddress) // contains the new contract address
})
.on('confirmation', function(confirmationNumber, receipt){ ... })
.then(function(newContractInstance){
    console.log(newContractInstance.options.address) // instance with the new contract address
});


// When the data is already set as an option to the contract itself
myContract.options.data = '0x12345...';

myContract.deploy({
    arguments: [123, 'My String']
})
.send({
    from: '0x1234567890123456789012345678901234567891',
    gas: 1500000,
    gasPrice: '30000000000000'
})
.then(function(newContractInstance){
    console.log(newContractInstance.options.address) // instance with the new contract address
});


// Simply encoding
myContract.deploy({
    data: '0x12345...',
    arguments: [123, 'My String']
})
.encodeABI();
> '0x12345...0000012345678765432'


// Gas estimation
myContract.deploy({
    data: '0x12345...',
    arguments: [123, 'My String']
})
.estimateGas(function(err, gas){
    console.log(gas);
});

methods

myContract.methods.myMethod([param1[, param2[, ...]]])

Creates a transaction object for that method, which then can be called, send, estimated.

The methods of this smart contract are available through:

  • The name: myContract.methods.myMethod(123)
  • The name with parameters: myContract.methods['myMethod(uint256)'](123)
  • The signature: myContract.methods['0x58cf5f10'](123)

This allows calling functions with same name but different parameters from the JavaScript contract object.

Parameters

Parameters of any method depend on the smart contracts methods, defined in the JSON interface.

Returns

Object: The transaction object:

  • Array - arguments: The arguments passed to the method before. They can be changed.
  • Function - call: Will call the “constant” method and execute its smart contract method in the EVM without sending a transaction (Can’t alter the smart contract state).
  • Function - send: Will send a transaction to the smart contract and execute its method (Can alter the smart contract state).
  • Function - estimateGas: Will estimate the gas used when the method would be executed on chain.
  • Function - encodeABI: Encodes the ABI for this method. This can be send using a transaction, call the method or passing into another smart contracts method as argument.
For details to the methods see the documentation below.

Example

// calling a method

myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result){
    ...
});

// or sending and using a promise
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(receipt){
    // receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
});

// or sending and using the events

myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.on('transactionHash', function(hash){
    ...
})
.on('receipt', function(receipt){
    ...
})
.on('confirmation', function(confirmationNumber, receipt){
    ...
})
.on('error', console.error);

methods.myMethod.call

myContract.methods.myMethod([param1[, param2[, ...]]]).call(options[, callback])

Will call a “constant” method and execute its smart contract method in the EVM without sending any transaction. Note calling can not alter the smart contract state.

Parameters

  1. options - Object (optional): The options used for calling.
    • from - String (optional): The address the call “transaction” should be made from.
    • gasPrice - String (optional): The gas price in wei to use for this call “transaction”.
    • gas - Number (optional): The maximum gas provided for this call “transaction” (gas limit).
  2. callback - Function (optional): This callback will be fired with the result of the smart contract method execution as the second argument, or with an error object as the first argument.

Returns

Promise returns Mixed: The return value(s) of the smart contract method. If it returns a single value, it’s returned as is. If it has multiple return values they are returned as an object with properties and indices:

Example

// using the callback
myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, result){
    ...
});

// using the promise
myContract.methods.myMethod(123).call({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(result){
    ...
});


// MULTI-ARGUMENT RETURN:

// Solidity
contract MyContract {
    function myFunction() returns(uint256 myNumber, string myString) {
        return (23456, "Hello!%");
    }
}

// web3.js
var MyContract = new web3.eth.contract(abi, address);
MyContract.methods.myFunction().call()
.then(console.log);
> Result {
    myNumber: '23456',
    myString: 'Hello!%',
    0: '23456', // these are here as fallbacks if the name is not know or given
    1: 'Hello!%'
}


// SINGLE-ARGUMENT RETURN:

// Solidity
contract MyContract {
    function myFunction() returns(string myString) {
        return "Hello!%";
    }
}

// web3.js
var MyContract = new web3.eth.contract(abi, address);
MyContract.methods.myFunction().call()
.then(console.log);
> "Hello!%"

methods.myMethod.send

myContract.methods.myMethod([param1[, param2[, ...]]]).send(options[, callback])

Will send a transaction to the smart contract and execute its method. Note this can alter the smart contract state.

Parameters

  1. options - Object: The options used for sending.
    • from - String: The address the transaction should be sent from.
    • gasPrice - String (optional): The gas price in wei to use for this transaction.
    • gas - Number (optional): The maximum gas provided for this transaction (gas limit).
  2. callback - Function (optional): This callback will be fired first with the “transactionHash”, or with an error object as the first argument.

Returns

The callback will return the 32 bytes transaction hash.

PromiEvent: A promise combined event emitter. Will be resolved when the transaction receipt is available, OR if this send() is called from a someContract.deploy(), then the promise will resolve with the new contract instance. Additionally the following events are available:

  • "transactionHash" returns String: is fired right after the transaction is sent and a transaction hash is available.
  • "receipt" returns Object: is fired when the transaction receipt is available. Receipts from contracts will have no logs property, but instead an events property with event names as keys and events as properties. See getPastEvents return values for details about the returned event object.
  • "confirmation" returns Number, Object: is fired for every confirmation up to the 24th confirmation. Receives the confirmation number as the first and the receipt as the second argument. Fired from confirmation 0 on, which is the block where it’s minded.
  • "error" returns Error: is fired if an error occurs during sending. If a out of gas error, the second parameter is the receipt.

Example

// using the callback
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'}, function(error, transactionHash){
    ...
});

// using the promise
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(receipt){
    // receipt can also be a new contract instance, when coming from a "contract.deploy({...}).send()"
});


// using the event emitter
myContract.methods.myMethod(123).send({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.on('transactionHash', function(hash){
    ...
})
.on('confirmation', function(confirmationNumber, receipt){
    ...
})
.on('receipt', function(receipt){
    // receipt example
    console.log(receipt);
    > {
        "transactionHash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
        "transactionIndex": 0,
        "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
        "blockNumber": 3,
        "contractAddress": "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
        "cumulativeGasUsed": 314159,
        "gasUsed": 30234,
        "events": {
            "MyEvent": {
                returnValues: {
                    myIndexedParam: 20,
                    myOtherIndexedParam: '0x123456789...',
                    myNonIndexParam: 'My String'
                },
                raw: {
                    data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                    topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
                },
                event: 'MyEvent',
                signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                logIndex: 0,
                transactionIndex: 0,
                transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
                blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
                blockNumber: 1234,
                address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
            },
            "MyOtherEvent": {
                ...
            }
        }
    }
})
.on('error', console.error); // If there's an out of gas error the second parameter is the receipt.

methods.myMethod.estimateGas

myContract.methods.myMethod([param1[, param2[, ...]]]).estimateGas(options[, callback])

Will call estimate the gas a method execution will take when executed in the EVM without. The estimation can differ from the actual gas used when later sending a transaction, as the state of the smart contract can be different at that time.

Parameters

  1. options - Object (optional): The options used for calling.
    • from - String (optional): The address the call “transaction” should be made from.
    • gas - Number (optional): The maximum gas provided for this call “transaction” (gas limit). Setting a specific value helps to detect out of gas errors. If all gas is used it will return the same number.
  2. callback - Function (optional): This callback will be fired with the result of the gas estimation as the second argument, or with an error object as the first argument.

Returns

Promise returns Number: The gas amount estimated.

Example

// using the callback
myContract.methods.myMethod(123).estimateGas({gas: 5000000}, function(error, gasAmount){
    if(gasAmount == 5000000)
        console.log('Method ran out of gas');
});

// using the promise
myContract.methods.myMethod(123).estimateGas({from: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'})
.then(function(gasAmount){
    ...
})
.catch(function(error){
    ...
});

methods.myMethod.encodeABI

myContract.methods.myMethod([param1[, param2[, ...]]]).encodeABI()

Encodes the ABI for this method. This can be used to send a transaction, call a method, or pass it into another smart contracts method as arguments.

Parameters

none

Returns

String: The encoded ABI byte code to send via a transaction or call.

Example

myContract.methods.myMethod(123).encodeABI();
> '0x58cf5f1000000000000000000000000000000000000000000000000000000000000007B'

= Events =


once

myContract.once(event[, options], callback)

Subscribes to an event and unsubscribes immediately after the first event or error. Will only fire for a single event.

Parameters

  1. event - String: The name of the event in the contract, or "allEvents" to get all events.
  2. options - Object (optional): The options used for deployment.
    • filter - Object (optional): Lets you filter events by indexed parameters, e.g. {filter: {myNumber: [12,13]}} means all events where “myNumber” is 12 or 13.
    • topics - Array (optional): This allows you to manually set the topics for the event filter. If given the filter property and event signature, (topic[0]) will not be set automatically.
  3. callback - Function: This callback will be fired for the first event as the second argument, or an error as the first argument. See getPastEvents return values for details about the event structure.

Returns

undefined

Example

myContract.once('MyEvent', {
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
    fromBlock: 0
}, function(error, event){ console.log(event); });

// event output example
> {
    returnValues: {
        myIndexedParam: 20,
        myOtherIndexedParam: '0x123456789...',
        myNonIndexParam: 'My String'
    },
    raw: {
        data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
        topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
    },
    event: 'MyEvent',
    signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    logIndex: 0,
    transactionIndex: 0,
    transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
    blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    blockNumber: 1234,
    address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
}

events

myContract.events.MyEvent([options][, callback])

Subscribe to an event

Parameters

  1. options - Object (optional): The options used for deployment.
    • filter - Object (optional): Let you filter events by indexed parameters, e.g. {filter: {myNumber: [12,13]}} means all events where “myNumber” is 12 or 13.
    • fromBlock - Number (optional): The block number from which to get events on.
    • topics - Array (optional): This allows to manually set the topics for the event filter. If given the filter property and event signature, (topic[0]) will not be set automatically.
  2. callback - Function (optional): This callback will be fired for each event as the second argument, or an error as the first argument.

Returns

EventEmitter: The event emitter has the following events:

  • "data" returns Object: Fires on each incoming event with the event object as argument.
  • "changed" returns Object: Fires on each event which was removed from the blockchain. The event will have the additional property "removed: true".
  • "error" returns Object: Fires when an error in the subscription occours.

The structure of the returned event Object looks as follows:

  • event - String: The event name.
  • signature - String|Null: The event signature, null if it’s an anonymous event.
  • address - String: Address this event originated from.
  • returnValues - Object: The return values coming from the event, e.g. {myVar: 1, myVar2: '0x234...'}.
  • logIndex - Number: Integer of the event index position in the block.
  • transactionIndex - Number: Integer of the transaction’s index position the event was created in.
  • transactionHash 32 Bytes - String: Hash of the transaction this event was created in.
  • blockHash 32 Bytes - String: Hash of the block this event was created in. null when it’s still pending.
  • blockNumber - Number: The block number this log was created in. null when still pending.
  • raw.data - String: The data containing non-indexed log parameter.
  • raw.topics - Array: An array with max 4 32 Byte topics, topic 1-3 contains indexed parameters of the event.

Example

myContract.events.MyEvent({
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
    fromBlock: 0
}, function(error, event){ console.log(event); })
.on('data', function(event){
    console.log(event); // same results as the optional callback above
})
.on('changed', function(event){
    // remove event from local database
})
.on('error', console.error);

// event output example
> {
    returnValues: {
        myIndexedParam: 20,
        myOtherIndexedParam: '0x123456789...',
        myNonIndexParam: 'My String'
    },
    raw: {
        data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
        topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
    },
    event: 'MyEvent',
    signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    logIndex: 0,
    transactionIndex: 0,
    transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
    blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    blockNumber: 1234,
    address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
}

events.allEvents

myContract.events.allEvents([options][, callback])

Same as events but receives all events from this smart contract. Optionally the filter property can filter those events.


getPastEvents

myContract.getPastEvents(event[, options][, callback])

Gets past events for this contract.

Parameters

  1. event - String: The name of the event in the contract, or "allEvents" to get all events.
  2. options - Object (optional): The options used for deployment.
    • filter - Object (optional): Lets you filter events by indexed parameters, e.g. {filter: {myNumber: [12,13]}} means all events where “myNumber” is 12 or 13.
    • fromBlock - Number (optional): The block number from which to get events on.
    • toBlock - Number (optional): The block number to get events up to (Defaults to "latest").
    • topics - Array (optional): This allows manually setting the topics for the event filter. If given the filter property and event signature, (topic[0]) will not be set automatically.
  3. callback - Function (optional): This callback will be fired with an array of event logs as the second argument, or an error as the first argument.

Returns

Promise returns Array: An array with the past event Objects, matching the given event name and filter.

For the structure of a returned event Object see getPastEvents return values.

Example

myContract.getPastEvents('MyEvent', {
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
    fromBlock: 0,
    toBlock: 'latest'
}, function(error, events){ console.log(events); })
.then(function(events){
    console.log(events) // same results as the optional callback above
});

> [{
    returnValues: {
        myIndexedParam: 20,
        myOtherIndexedParam: '0x123456789...',
        myNonIndexParam: 'My String'
    },
    raw: {
        data: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
        topics: ['0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7', '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385']
    },
    event: 'MyEvent',
    signature: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    logIndex: 0,
    transactionIndex: 0,
    transactionHash: '0x7f9fade1c0d57a7af66ab4ead79fade1c0d57a7af66ab4ead7c2c2eb7b11a91385',
    blockHash: '0xfd43ade1c09fade1c0d57a7af66ab4ead7c2c2eb7b11a91ffdd57a7af66ab4ead7',
    blockNumber: 1234,
    address: '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe'
},{
    ...
}]