# caver.klay.Contract

The `caver.klay.Contract` object makes it easy to interact with smart contracts on the Klaytn blockchain. When you create a new contract object, you give it the JSON interface of the respective smart contract and caver 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.

## new contract <a href="#new-contract" id="new-contract"></a>

```javascript
new caver.klay.Contract(jsonInterface [, address] [, options])
```

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

**Parameters**

| Name          | Type   | Description                                                                                                              |
| ------------- | ------ | ------------------------------------------------------------------------------------------------------------------------ |
| jsonInterface | Object | The JSON interface for the contract to instantiate                                                                       |
| address       | String | (optional) The address of the smart contract to call. Can be added later using `myContract.options.address = '0x1234..'` |
| options       | Object | (optional) The options of the contract. See the table below for the details.                                             |

The options object contains the following:

| Name     | Type   | Description                                                                     |
| -------- | ------ | ------------------------------------------------------------------------------- |
| from     | String | (optional) The address from which transactions should be made.                  |
| gasPrice | String | (optional) The gas price in peb to use for transactions.                        |
| gas      | Number | (optional) The maximum gas provided for a transaction (gas limit).              |
| data     | String | (optional) The byte code of the contract. Used when the contract gets deployed. |

**Return Value**

| Type   | Description                                            |
| ------ | ------------------------------------------------------ |
| Object | The contract instance with all its methods and events. |

**Example**

```javascript
var myContract = new caver.klay.Contract([...], '0xde0B295669a9FD93d5F28D9Ec85E40f4cb697BAe', {
      from: '0x1234567890123456789012345678901234567891', // default from address
      gasPrice: '25000000000' // default gas price in peb, 25 Gpeb in this case
});

var myContract = new caver.klay.Contract([...], 'myContract', {
      from: '0x1234567890123456789012345678901234567891', // default from address
      gasPrice: '25000000000' // default gas price in peb, 25 Gpeb in this case
});
```

## options <a href="#options" id="options"></a>

```javascript
myContract.options
```

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

**Properties**

| Name          | Type   | Description                                                                                   |
| ------------- | ------ | --------------------------------------------------------------------------------------------- |
| address       | String | The address where the contract is deployed. Also see [options.address](#options-address).     |
| jsonInterface | Array  | The JSON interface of the contract. Also see [options.jsonInterface](#options-jsoninterface). |
| data          | String | The byte code of the contract. Used when the contract gets deployed.                          |
| from          | String | 트랜잭션이 만들어진 송신자 주소.                                                                            |
| gasPrice      | String | The gas price in peb to use for transactions.                                                 |
| gas           | Number | The maximum gas provided for a transaction (gas limit).                                       |

**Example**

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

> myContract.options.from = '0x1234567890123456789012345678901234567891'; // default from address
> myContract.options.gasPrice = '25000000000000'; // default gas price in peb
> myContract.options.gas = 5000000; // provide as fallback always 5M gas
```

## options.address <a href="#options-address" id="options-address"></a>

```javascript
myContract.options.address
```

The address used for this contract instance `myContract`. All transactions generated by caver-js from this contract will contain this address as the "to". 주소는 소문자로 저장됩니다.

**Property**

| Name    | Type      | Description |
| ------- | --------- | ----------- |
| address | String \\ | `null`      |

**Example**

```javascript
>  myContract.options.address;
'0xde0b295669a9fd93d5f28d9ec85e40f4cb697bae'

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

## options.jsonInterface <a href="#options-jsoninterface" id="options-jsoninterface"></a>

```javascript
myContract.options.jsonInterface
```

The JSON interface object derived from the ABI of this contract `myContract`.

**Property**

| Name          | Type  | Description                                                                                                            |
| ------------- | ----- | ---------------------------------------------------------------------------------------------------------------------- |
| jsonInterface | Array | The JSON interface for this contract. Re-setting this will regenerate the methods and events of the contract instance. |

**Example**

```javascript
> 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 = [...];
```

## clone <a href="#clone" id="clone"></a>

```javascript
myContract.clone()
```

Clones the current contract instance.

**Parameters**

None

**Return Value**

| Type   | Description                       |
| ------ | --------------------------------- |
| Object | The new cloned contract instance. |

**Example**

```javascript
> var contract1 = new caver.klay.Contract(abi, address, {gasPrice: '12345678', from: fromAddress});
> var contract2 = contract1.clone();
> contract2.options.address = address2;
> (contract1.options.address !== contract2.options.address);
true
```

## deploy <a href="#deploy" id="deploy"></a>

```javascript
myContract.deploy(options)
```

컨트랙트를 Klaytn 블록체인에 배포합니다. After successful deployment, the promise will be resolved with a new contract instance.

**Parameters**

`options`: 배포에 사용되는 옵션 객체:

| Name      | Type   | Description                                                                |
| --------- | ------ | -------------------------------------------------------------------------- |
| data      | String | The byte code of the contract.                                             |
| arguments | Array  | (optional) The arguments that get passed to the constructor on deployment. |

**Return Value**

`Object`: 트랜잭션 객체:

| Type     | Description                                                                                                                   |
| -------- | ----------------------------------------------------------------------------------------------------------------------------- |
| Array    | arguments: 이전에 메소드에 전달되었던 인자. 이들은 변경될 수 있습니다.                                                                                 |
| Function | [send](#methods-mymethod-send): Will deploy the contract. 프로미스는 영수증 대신 새 컨트랙트 인스턴스를 반환할 것입니다.                                 |
| Function | [estimateGas](#methods-mymethod-estimategas): Will estimate the gas used for the deployment.                                  |
| Function | [encodeABI](#methods-mymethod-encodeabi): Encodes the ABI of the deployment, which is contract data + constructor parameters. |

**Example**

```javascript
> myContract.deploy({
      data: '0x12345...',
      arguments: [123, 'My String']
  })
  .send({
      from: '0x1234567890123456789012345678901234567891',
      gas: 1500000,
      value: 0,
  }, function(error, transactionHash) { ... })
  .on('error', function(error) { ... })
  .on('transactionHash', function(transactionHash) { ... })
  .on('receipt', function(receipt) {
     console.log(receipt.contractAddress) // contains the new contract address
   })
  .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,
      value: 0,
  })
  .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 <a href="#methods" id="methods"></a>

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

Creates a transaction object for that method, which then can be called, sent, estimated or ABI encoded.

이 스마트 컨트랙트의 메소드는 다음을 통해 이용할 수 있습니다:

* 이름: `myContract.methods.myMethod(123)`
* 매개변수가 있는 이름: `myContract.methods['myMethod(uint256)'](123)`
* The signature\*: `myContract.methods['0x58cf5f10'](123)`

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

## cf) \*Function signature (Function selector) <a href="#cf-function-signature-function-selector" id="cf-function-signature-function-selector"></a>

The first four bytes of the call data for a function call specifies the function to be called.\
It is the first (left, high-order in big-endian) four bytes of the Keccak-256 (SHA-3) hash of the signature of the function.

The function signature can be made by 2 different methods.\
`1. caver.klay.abi.encodeFunctionSignature('funcName(paramType1,paramType2,...)')`\
`2. caver.utils.sha3('funcName(paramType1,paramType2,...)').substr(0, 10)`

ex)

```javascript
caver.klay.abi.encodeFunctionSignature('myMethod(uint256)')
> 0x58cf5f10

caver.utils.sha3('myMethod(uint256)').substr(0, 10)
> 0x58cf5f10
```

**Parameters**

모든 메소드의 매개변수는 JSON 인터페이스에 정의된 스마트 컨트랙트 메소드에 의존합니다.

**Return Value**

`Object`: The transaction object:

| Type     | Description                                                                                                                                                                                                |
| -------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Array    | arguments: The arguments passed to the method before. They can be changed.                                                                                                                                 |
| Function | [call](#methods-mymethod-call): Will call the "constant" method and execute its smart contract method in the Klaytn Virtual Machine without sending a transaction (cannot alter the smart contract state). |
| Function | [send](#methods-mymethod-send): Will send a transaction to the smart contract and execute its method (can alter the smart contract state).                                                                 |
| Function | [estimateGas](#methods-mymethod-estimategas): Will estimate the gas used when the method would be executed on the blockchain.                                                                              |
| Function | [encodeABI](#methods-mymethod-encodeabi): Encodes the ABI for this method. 트랜잭션을 사용하여 메소드를 호출하거나 인수로써 다른 스마트 컨트랙트 메소드에 전달될 수 있습니다.                                                                         |

**Example**

```javascript
// 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('error', console.error);
```

## methods.myMethod.call <a href="#methods-mymethod-call" id="methods-mymethod-call"></a>

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

Will call a "constant" method and execute its smart contract method in the Klaytn Virtual Machine without sending any transaction. Note that calling cannot alter the smart contract state.

**Parameters**

| Name     | Type     | Description                                                                                                                                                          |
| -------- | -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| options  | Object   | (optional) The options used for calling. See the table below for the details.                                                                                        |
| 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. |

The options object can contain the following:

| Name     | Type   | Description                                                                  |
| -------- | ------ | ---------------------------------------------------------------------------- |
| from     | String | (optional) The address the call “transaction” should be made from.           |
| gasPrice | String | (optional) The gas price in peb to use for this call "transaction".          |
| gas      | Number | (optional) The maximum gas provided for this call "transaction" (gas limit). |

**Return Value**

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

**Example**

```javascript
// 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) {
      ...
  });
```

```
// Solidity: MULTI-ARGUMENT RETURN
contract MyContract {
    function myFunction() returns(uint256 myNumber, string myString) {
        return (23456, "Hello!%");
    }
}
```

```javascript
> var MyContract = new caver.klay.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 known or given
      1: 'Hello!%'
}
```

```
// Solidity: SINGLE-ARGUMENT RETURN
contract MyContract {
    function myFunction() returns(string myString) {
        return "Hello!%";
    }
}
```

```javascript
> var MyContract = new caver.klay.Contract(abi, address);
> MyContract.methods.myFunction().call().then(console.log);
"Hello!%"
```

## methods.myMethod.send <a href="#methods-mymethod-send" id="methods-mymethod-send"></a>

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

스마트 컨트랙트에 트랜잭션을 보내고 그 메소드를 실행합니다. Note that this can alter the smart contract state.

**Parameters**

| Name     | Type     | Description                                                                                                             |
| -------- | -------- | ----------------------------------------------------------------------------------------------------------------------- |
| options  | Object   | The options used for sending. See the table below for the details.                                                      |
| callback | Function | (optional) This callback will be fired first with the "transactionHash", or with an error object as the first argument. |

The options object can contain the following:

| Name     | Type      | Description                                                  |
| -------- | --------- | ------------------------------------------------------------ |
| from     | String    | The address from which the transaction should be sent.       |
| gasPrice | String    | (optional) The gas price in peb to use for this transaction. |
| gas      | Number    | The maximum gas provided for this transaction (gas limit).   |
| value    | Number \\ | String \| BN \| BigNumber                                    |

**Return Value**

`callback`은 32바이트 트랜잭션 해시를 반환합니다.

`PromiEvent`: 프로미스(promise)가 조합된 이벤트 이미터(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 be resolved with the new contract instance. 추가로 다음과 같은 이벤트를 사용할 수 있습니다:

| Name            | Type   | Description                                                                                                                                                                                           |
| --------------- | ------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| transactionHash | String | 트랜잭션이 전송된 직후 및 트랜잭션 해시를 사용할 수 있을 때 발생합니다.                                                                                                                                                             |
| receipt         | Object | 트랜잭션 영수증을 사용할 수 있을 때 발생합니다. 컨트랙트의 영수증에는 `logs` 속성이 없지만, 대신 이벤트 이름을 키로, 이벤트를 속성으로 하는 `events` 속성이 있습니다. See [getPastEvents return values](#getpastevents) for details about the returned event object. |
| error           | Error  | 전송 중 오류가 발생하면 발생됩니다. On an out-of-gas error, the second parameter is the receipt.                                                                                                                     |

**Example**

```javascript
// 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('receipt', function(receipt) {
    console.log(receipt);
  })
  .on('error', console.error); // If there is an out-of-gas error, the second parameter is the receipt.

// receipt example
{
   "transactionHash": "0x9fc76417374aa880d4449a1f7f31ec597f00b1f6f3dd2d66f4c9c6c445836d8b",
   "transactionIndex": 0,
   "blockHash": "0xef95f2f1ed3ca60b048b4bf67cde2195961e0bba6f70bcbea9a2c4e133e34b46",
   "blockNumber": 3,
   "contractAddress": "0x11f4d0A3c12e86B4b5F39B213F7E19D048276DAe",
   "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": {
      ...
    },
    "MyMultipleEvent":[{...}, {...}] // If there are a multiple of the same events, they will be in an array.
  }
}
```

## methods.myMethod.estimateGas <a href="#methods-mymethod-estimategas" id="methods-mymethod-estimategas"></a>

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

Will estimate the gas that a method execution will take when executed in the Klaytn Virtual Machine. 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**

| Name     | Type     | Description                                                                                                                                         |
| -------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------- |
| options  | Object   | (optional) The options used for calling. See the table below for the details.                                                                       |
| 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. |

The options object can contain the following:

| Name  | Type      | Description                                                                                                                                                                                  |
| ----- | --------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| from  | String    | (optional) The address from which the call "transaction" should be made.                                                                                                                     |
| 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. |
| value | Number \\ | String \| BN \| BigNumber                                                                                                                                                                    |

**Return Value**

`Promise`는 `Number`를 반환합니다 - 모의 호출/트랜잭션에 사용된 가스.

**Example**

```javascript
// 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 <a href="#methods-mymethod-encodeabi" id="methods-mymethod-encodeabi"></a>

```javascript
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 contract method as arguments.

**Parameters**

None

**Return Value**

| Type   | Description                                                  |
| ------ | ------------------------------------------------------------ |
| String | The encoded ABI byte code to send via a transaction or call. |

**Example**

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

## once <a href="#once" id="once"></a>

```javascript
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**

| Name     | Type     | Description                                                                                                                                                                                         |
| -------- | -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| event    | String   | 컨트랙트, 또는 모든 이벤트를 받기 위한 `"allEvents"`에서의 이벤트 이름.                                                                                                                                                     |
| options  | Object   | (optional) The options used for deployment. See the table below for the details.                                                                                                                    |
| 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](#getpastevents) for details about the event structure. |

The options object can contain the following:

| Name   | Type   | Description                                                                                                                                     |
| ------ | ------ | ----------------------------------------------------------------------------------------------------------------------------------------------- |
| 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. 필터 특성 및 이벤트 서명이 제공되면, `topic[0]` 가 자동으로 설정되지 않습니다.                  |

**Return Value**

`undefined`

**Example**

```javascript
> myContract.once('MyEvent', {
    filter: {myIndexedParam: [20,23], myOtherIndexedParam: '0x123456789...'}, // Using an array means OR: e.g. 20 or 23
  }, 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 <a href="#events" id="events"></a>

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

이벤트를 구독합니다.

**Parameters**

| Name     | Type     | Description                                                                                                      |
| -------- | -------- | ---------------------------------------------------------------------------------------------------------------- |
| options  | Object   | (optional) The options used for deployment. See the table below for the details.                                 |
| callback | Function | (optional) This callback will be fired for each event as the second argument, or an error as the first argument. |

The options object can contain the following:

| Name      | Type   | Description                                                                                                                                                         |
| --------- | ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 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.                                                                                                            |
| 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. |

**Return Value**

`EventEmitter`: 이벤트 이미터는 다음 이벤트를 가집니다:

| Name  | Type   | Description                  |
| ----- | ------ | ---------------------------- |
| data  | Object | 이벤트 객체를 인수로 각 수신 이벤트를 발생합니다. |
| error | Object | 구독 오류가 발생하면 발생합니다.           |

반환된 이벤트 `Object`의 구조는 다음과 같습니다:

| Name             | Type           | Description                                                                                                                   |
| ---------------- | -------------- | ----------------------------------------------------------------------------------------------------------------------------- |
| event            | String         | 이벤트 이름.                                                                                                                       |
| signature        | String \\      | `null`                                                                                                                        |
| address          | String         | 이 이벤트가 발생한 주소.                                                                                                                |
| returnValues     | Object         | The return values coming from the event, *e.g.*, `{myVar: 1, myVar2: '0x234...'}`.                                            |
| logIndex         | Number         | 블록에서 이벤트 인덱스 위치의 정수값.                                                                                                         |
| transactionIndex | Number         | 이벤트가 생성된 트랜잭션의 인덱스 위치의 정수값.                                                                                                   |
| transactionHash  | 32-byte String | 이 이벤트가 생성된 블록의 해시. 아직 보류 중인 경우 `null`.                                                                                        |
| blockHash        | 32-byte String | Hash of the block this event was created in. `null` when it is still pending.                                                 |
| blockNumber      | Number         | 이 로그가 생성된 블록 번호. 아직 보류 중인 경우 `null`.                                                                                          |
| raw\.data        | String         | 색인화되지 않은 로그 매개변수를 포함하는 데이터.                                                                                                   |
| raw\.topics      | Array          | 최대 4개의 32바이트 주제를 가진 배열, 주제 1-3은 이벤트의 색인화된 매개변수가 포함됩니다.                                                                        |
| id               | String         | 로그 식별자. It is made through concatenating "log\_" string with `keccak256(blockHash + transactionHash + logIndex).substr(0, 8)` |

**Example**

```javascript
> 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('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',
    id: 'log_41d221bc',
}
```

## events.allEvents <a href="#events-allevents" id="events-allevents"></a>

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

Same as [events](#events) but receives all events from this smart contract. 선택적으로 filter 속성은 해당 이벤트를 필터링할 수 있습니다.

## getPastEvents <a href="#getpastevents" id="getpastevents"></a>

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

이 컨트랙트의 이전 이벤트를 가져옵니다.

**Parameters**

| Name     | Type     | Description                                                                                                                   |
| -------- | -------- | ----------------------------------------------------------------------------------------------------------------------------- |
| event    | String   | The name of the event in the contract, or `"allEvents"` to get all events.                                                    |
| options  | Object   | (optional) The options used for deployment. See the table below for the details.                                              |
| 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. |

옵션 개체에는 다음이 포함됩니다:

| Name      | Type   | Description                                                                                                                                                          |
| --------- | ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| 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. |

**Return Value**

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

**Example**

```javascript
> 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'
},{
      ...
}]
```