web3.eth.subscribe — web3.js 1.0.0 documentation

subscribe¶

web3.eth.subscribe(type [, options] [, callback]);

Parameters¶

String - 구독하고자 하는 이벤트
Mixed - (optional) 구독 유형에 따른 선택적 인자
Function - (optional) 옵셔널 콜백, 첫 번째 매개 변수로 오류 개체를 반환하고 두 번째 매개 변수로 결과를 반환합니다. 또한 들어오는 각각의 구독에 대해 호출되며 구독 자체는 3개의 매개 변수로 호출됩니다

Returns¶

EventEmitter - 서브스크립션 개체

subscription.id: 구독을 식별하고 구독을 취소하는 데 사용되는 구독 ID.

subscription.subscribe([callback]): 동일한 파라미터로 재구독하는 데 사용할 수 있습니다.

subscription.unsubscribe([callback]): 구독을 취소하고 성공하면 콜백에 TRUE를 반환합니다.

subscription.arguments: 다시 구독할 때 사용되는 구독 인자 입니다.

on("data") returns Object: 로그 개체를 인수로 하여 들어오는 각 로그에서 실행합니다.

on("changed") returns Object: Fires on each log which was removed from the blockchain. The log will have the additional property "removed: true".

on("error") returns Object: Fires when an error in the subscription occurs.

on("connected") returns String: Fires once after the subscription successfully connected. Returns the subscription id.

알림 반환값¶

Mixed - 구독한 이벤트에 따라 다른 결과.

Example¶

var subscription = web3.eth.subscribe('logs', {
    address: '0x123456..',
    topics: ['0x12345...']
}, function(error, result){
    if (!error)
        console.log(result);
});

// 구독 취소
subscription.unsubscribe(function(error, success){
    if(success)
        console.log('Successfully unsubscribed!');
});

clearSubscriptions¶

web3.eth.clearSubscriptions()

구독 초기화

..note:: "web3-ssh"와 같은 다른 패키지의 구독을 리셋하지는 않을 것 입니다. 그런 패키지들은 각각의 요청매니저(RequestManager)를 사용합니다

Parameters¶

Boolean: 구독을 계속 불러오고 있을경우 true 를 반환합니다.

Returns¶

Boolean

Example¶

web3.eth.subscribe('logs', {} ,function(){ ... });

...

web3.eth.clearSubscriptions();

subscribe("pendingTransactions")¶

web3.eth.subscribe('pendingTransactions' [, callback]);

String - "pendingTransactions", 구독의 종류
Function - (optional) 옵셔널 콜백, 첫 번째 매개 변수로 오류 개체를 반환하고 두 번째 매개 변수로 결과를 반환합니다. 또한 들어오는 각 구독에 대해 호출될 것입니다.

Returns¶

EventEmitter: An subscription instance as an event emitter with the following events:

"data" returns String: Fires on each incoming pending transaction and returns the transaction hash.
"error" returns Object: Fires when an error in the subscription occurs.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
String - Second parameter is the transaction hash.

Example¶

var subscription = web3.eth.subscribe('pendingTransactions', function(error, result){
    if (!error)
        console.log(result);
})
.on("data", function(transaction){
    console.log(transaction);
});

// unsubscribes the subscription
subscription.unsubscribe(function(error, success){
    if(success)
        console.log('Successfully unsubscribed!');
});

subscribe("newBlockHeaders")¶

web3.eth.subscribe('newBlockHeaders' [, callback]);

Subscribes to incoming block headers. This can be used as timer to check for changes on the blockchain.

Parameters¶

String - "newBlockHeaders", the type of the subscription.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.

Returns¶

EventEmitter: An subscription instance as an event emitter with the following events:

"data" returns Object: Fires on each incoming block header.
"error" returns Object: Fires when an error in the subscription occurs.
"connected" returns Number: Fires once after the subscription successfully connected. Returns the subscription id.

The structure of a returned block header is as follows:

number - Number: The block number. null when its pending block.

hash 32 Bytes - String: Hash of the block. null when its pending block.

parentHash 32 Bytes - String: Hash of the parent block.

nonce 8 Bytes - String: Hash of the generated proof-of-work. null when its pending block.

sha3Uncles 32 Bytes - String: SHA3 of the uncles data in the block.

logsBloom 256 Bytes - String: The bloom filter for the logs of the block. null when its pending block.

transactionsRoot 32 Bytes - String: The root of the transaction trie of the block

stateRoot 32 Bytes - String: The root of the final state trie of the block.

receiptsRoot 32 Bytes - String: The root of the receipts.

miner - String: The address of the beneficiary to whom the mining rewards were given.

extraData - String: The "extra data" field of this block.

gasLimit - Number: The maximum gas allowed in this block.

gasUsed - Number: The total used gas by all transactions in this block.

timestamp - Number: The unix timestamp for when the block was collated.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
Object - The block header object like above.

Example¶

var subscription = web3.eth.subscribe('newBlockHeaders', function(error, result){
    if (!error) {
        console.log(result);

        return;
    }

    console.error(error);
})
.on("connected", function(subscriptionId){
    console.log(subscriptionId);
})
.on("data", function(blockHeader){
    console.log(blockHeader);
})
.on("error", console.error);

// unsubscribes the subscription
subscription.unsubscribe(function(error, success){
    if (success) {
        console.log('Successfully unsubscribed!');
    }
});

subscribe("syncing")¶

web3.eth.subscribe('syncing' [, callback]);

Subscribe to syncing events. This will return an object when the node is syncing and when its finished syncing will return FALSE.

Parameters¶

String - "syncing", the type of the subscription.
Function - (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.

Returns¶

EventEmitter: An subscription instance as an event emitter with the following events:

"data" returns Object: Fires on each incoming sync object as argument.
"changed" returns Object: Fires when the synchronisation is started with true and when finished with false.
"error" returns Object: Fires when an error in the subscription occurs.

For the structure of a returned event Object see web3.eth.isSyncing return values.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
Object|Boolean - The syncing object, when started it will return true once or when finished it will return false once.

Example¶

var subscription = web3.eth.subscribe('syncing', function(error, sync){
    if (!error)
        console.log(sync);
})
.on("data", function(sync){
    // show some syncing stats
})
.on("changed", function(isSyncing){
    if(isSyncing) {
        // stop app operation
    } else {
        // regain app operation
    }
});

// unsubscribes the subscription
subscription.unsubscribe(function(error, success){
    if(success)
        console.log('Successfully unsubscribed!');
});

subscribe("logs")¶

web3.eth.subscribe('logs', options [, callback]);

Subscribes to incoming logs, filtered by the given options. If a valid numerical fromBlock options property is set, Web3 will retrieve logs beginning from this point, backfilling the response as necessary.

Parameters¶

"logs" - String, the type of the subscription.
Object - The subscription options

fromBlock - Number: The number of the earliest block. By default null.

address - String|Array: An address or a list of addresses to only get logs from particular account(s).

topics - Array: An array of values which must each appear in the log entries. The order is important, if you want to leave topics out use null, e.g. [null, '0x00...']. You can also pass another array for each topic with options for that topic e.g. [null, ['option1', 'option2']]

callback - Function: (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.

Returns¶

EventEmitter: An subscription instance as an event emitter with the following events:

"data" returns Object: Fires on each incoming log with the log object as argument.
"changed" returns Object: Fires on each log which was removed from the blockchain. The log will have the additional property "removed: true".
"error" returns Object: Fires when an error in the subscription occurs.
"connected" returns Number: Fires once after the subscription successfully connected. Returns the subscription id.

For the structure of a returned event Object see web3.eth.getPastEvents return values.

Notification returns¶

Object|Null - First parameter is an error object if the subscription failed.
Object - The log object like in web3.eth.getPastEvents return values.

Example¶

var subscription = web3.eth.subscribe('logs', {
    address: '0x123456..',
    topics: ['0x12345...']
}, function(error, result){
    if (!error)
        console.log(result);
})
.on("connected", function(subscriptionId){
    console.log(subscriptionId);
})
.on("data", function(log){
    console.log(log);
})
.on("changed", function(log){
});

// unsubscribes the subscription
subscription.unsubscribe(function(error, success){
    if(success)
        console.log('Successfully unsubscribed!');
});

web3.eth.subscribe¶

subscribe¶

Parameters¶

Returns¶

알림 반환값¶

Example¶

clearSubscriptions¶

Parameters¶

Returns¶

Example¶

subscribe("pendingTransactions")¶

Returns¶

Notification returns¶

Example¶

subscribe("newBlockHeaders")¶

Parameters¶

Returns¶

Notification returns¶

Example¶

subscribe("syncing")¶

Parameters¶

Returns¶

Notification returns¶

Example¶

subscribe("logs")¶

Parameters¶

Returns¶

Notification returns¶

Example¶