mirror of
https://github.com/status-im/web3.js.git
synced 2025-02-23 11:38:12 +00:00
330 lines
10 KiB
ReStructuredText
330 lines
10 KiB
ReStructuredText
.. _eth-subscribe:
|
|
|
|
|
|
=========
|
|
web3.eth.subscribe
|
|
=========
|
|
|
|
The ``web3.eth.subscribe`` function lets you subscribe to specifc events in the blockchain.
|
|
|
|
|
|
|
|
Subscription pattern
|
|
=====================
|
|
|
|
.. code-block:: javascript
|
|
|
|
web3.eth.subscribe(type [, options] [, callback]);
|
|
|
|
----------
|
|
Parameters
|
|
----------
|
|
|
|
1. ``String`` - The subscription, you want to subscribe to.
|
|
2. ``Mixed`` - (optional) Optional additional parameters, depending on the subscription type.
|
|
3. ``Function`` - (optional) Optional callback, returns an error object as first parameter and the result as second. Will be called for each incoming subscription.
|
|
|
|
.. _eth-subscription-return:
|
|
|
|
-------
|
|
Returns
|
|
-------
|
|
|
|
``EventEmitter`` - A Subscription instance
|
|
|
|
- ``subscription.id``: The subscription id, used to identify and unsubscribing the subscription.
|
|
- ``subscription.unsubscribe([callback])``: Unsubscribes the subscription and returns `TRUE` in the callback if successfull.
|
|
- ``on("data")`` returns ``Object``: Fires on each incoming log with the log object as argument.
|
|
- ``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 occours.
|
|
|
|
----------------
|
|
Callback returns
|
|
----------------
|
|
|
|
- ``Mixed`` - depends on the subscription, see the different subscriptions for more.
|
|
|
|
-------
|
|
Example
|
|
-------
|
|
|
|
.. code-block:: javascript
|
|
|
|
var subscription = web3.eth.subscribe('logs', {
|
|
address: '0x123456..',
|
|
topics: ['0x12345...']
|
|
}, function(error, result){
|
|
if (!error)
|
|
console.log(log);
|
|
});
|
|
|
|
// unsubscribes the subscription
|
|
subscription.unsubscribe(function(error, success){
|
|
if(success)
|
|
console.log('Successfully unsubscribed!');
|
|
});
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
pendingTransactions
|
|
=====================
|
|
|
|
.. code-block:: javascript
|
|
|
|
web3.eth.subscribe('pendingTransactions' [, callback]);
|
|
|
|
Subscribes to incoming pending transactions.
|
|
|
|
----------
|
|
Parameters
|
|
----------
|
|
|
|
1. ``String`` - ``"pendingTransactions"``, the type of the subscription.
|
|
2. ``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 :ref:`subscription instance <eth-subscription-return>` as an event emitter with the following events:
|
|
|
|
- ``"data"`` returns ``Object``: Fires on each incoming pending transaction.
|
|
- ``"error"`` returns ``Object``: Fires when an error in the subscription occours.
|
|
|
|
For the structure of the returned object see :ref:`web3.eth.getTransaction() return values <eth-gettransaction-return>`.
|
|
|
|
----------------
|
|
Callback returns
|
|
----------------
|
|
|
|
1. ``Object|Null`` - First parameter is an error object if the subscription failed.
|
|
2. ``Object`` - The block header object like above.
|
|
|
|
-------
|
|
Example
|
|
-------
|
|
|
|
|
|
.. code-block:: javascript
|
|
|
|
var subscription = web3.eth.subscribe('pendingTransactions', function(error, result){
|
|
if (!error)
|
|
console.log(transaction);
|
|
})
|
|
.on("data", function(transaction){
|
|
});
|
|
|
|
// unsubscribes the subscription
|
|
subscription.unsubscribe(function(error, success){
|
|
if(success)
|
|
console.log('Successfully unsubscribed!');
|
|
});
|
|
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
newBlockHeaders
|
|
=====================
|
|
|
|
.. code-block:: javascript
|
|
|
|
web3.eth.subscribe('newBlockHeaders' [, callback]);
|
|
|
|
Subscribes to incoming block headers. This can be used as timer to check for changes on the blockchain.
|
|
|
|
----------
|
|
Parameters
|
|
----------
|
|
|
|
1. ``String`` - ``"newBlockHeaders"``, the type of the subscription.
|
|
2. ``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 :ref:`subscription instance <eth-subscription-return>` 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 occours.
|
|
|
|
The structure of a returned block header is as follows:
|
|
|
|
- ``Number`` - ``number``: The block number. ``null`` when its pending block.
|
|
- ``String`` 32 Bytes - ``hash``: Hash of the block. ``null`` when its pending block.
|
|
- ``String`` 32 Bytes - ``parentHash``: Hash of the parent block.
|
|
- ``String`` 8 Bytes - ``nonce``: Hash of the generated proof-of-work. ``null`` when its pending block.
|
|
- ``String`` 32 Bytes - ``sha3Uncles``: SHA3 of the uncles data in the block.
|
|
- ``String`` 256 Bytes - ``logsBloom``: The bloom filter for the logs of the block. ``null`` when its pending block.
|
|
- ``String`` 32 Bytes - ``transactionsRoot``: The root of the transaction trie of the block
|
|
- ``String`` 32 Bytes - ``stateRoot``: The root of the final state trie of the block.
|
|
- ``String`` 32 Bytes - ``receiptRoot``: The root of the receipts.
|
|
- ``String`` - ``miner``: The address of the beneficiary to whom the mining rewards were given.
|
|
- ``String`` - ``extraData``: The "extra data" field of this block.
|
|
- ``Number`` - ``gasLimit``: The maximum gas allowed in this block.
|
|
- ``Number`` - ``gasUsed``: The total used gas by all transactions in this block.
|
|
- ``Number`` - ``timestamp``: The unix timestamp for when the block was collated.
|
|
|
|
----------------
|
|
Callback returns
|
|
----------------
|
|
|
|
1. ``Object|Null`` - First parameter is an error object if the subscription failed.
|
|
2. ``Object`` - The block header object like above.
|
|
|
|
-------
|
|
Example
|
|
-------
|
|
|
|
|
|
.. code-block:: javascript
|
|
|
|
var subscription = web3.eth.subscribe('newBlockHeaders', function(error, result){
|
|
if (!error)
|
|
console.log(blockHeader);
|
|
})
|
|
.on("data", function(blockHeader){
|
|
});
|
|
|
|
// unsubscribes the subscription
|
|
subscription.unsubscribe(function(error, success){
|
|
if(success)
|
|
console.log('Successfully unsubscribed!');
|
|
});
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
syncing
|
|
=====================
|
|
|
|
.. code-block:: javascript
|
|
|
|
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
|
|
----------
|
|
|
|
1. ``String`` - ``"syncing"``, the type of the subscription.
|
|
2. ``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 :ref:`subscription instance <eth-subscription-return>` 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 finsihed with ``FALSE``.
|
|
- ``"error"`` returns ``Object``: Fires when an error in the subscription occours.
|
|
|
|
For the structure of a returned event ``Object`` see :ref:`web3.eth.isSyncing return values <eth-issyncing-return>`.
|
|
|
|
----------------
|
|
Callback returns
|
|
----------------
|
|
|
|
1. ``Object|Null`` - First parameter is an error object if the subscription failed.
|
|
2. ``Object|Boolean`` - The syncing object, when started it will return ``TRUE`` once or when finished it will return `FALSE` once.
|
|
|
|
-------
|
|
Example
|
|
-------
|
|
|
|
|
|
.. code-block:: javascript
|
|
|
|
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!');
|
|
});
|
|
|
|
------------------------------------------------------------------------------
|
|
|
|
|
|
logs
|
|
=====================
|
|
|
|
.. code-block:: javascript
|
|
|
|
web3.eth.subscribe('logs', options [, callback]);
|
|
|
|
Subscribes to incoming logs, filtered by the given options.
|
|
|
|
----------
|
|
Parameters
|
|
----------
|
|
|
|
1. ``String`` - ``"logs"``, the type of the subscription.
|
|
2. ``Object`` - The subscription options
|
|
- ``Number`` - ``fromBlock``: The number of the earliest block. By default ``null``.
|
|
- ``String`` - ``address``: An address or a list of addresses to only get logs from particular account(s).
|
|
- ``Array`` - ``topics``: 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']]``
|
|
3. ``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 :ref:`subscription instance <eth-subscription-return>` 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 occours.
|
|
|
|
For the structure of a returned event ``Object`` see :ref:`web3.eth.getPastEvents return values <eth-getpastlogs-return>`.
|
|
|
|
----------------
|
|
Callback returns
|
|
----------------
|
|
|
|
1. ``Object|Null`` - First parameter is an error object if the subscription failed.
|
|
2. ``Object`` - The log object like in :ref:`web3.eth.getPastEvents return values <eth-getpastlogs-return>`.
|
|
|
|
-------
|
|
Example
|
|
-------
|
|
|
|
|
|
.. code-block:: javascript
|
|
|
|
var subscription = web3.eth.subscribe('logs', {
|
|
address: '0x123456..',
|
|
topics: ['0x12345...']
|
|
}, function(error, result){
|
|
if (!error)
|
|
console.log(log);
|
|
})
|
|
.on("data", function(log){
|
|
})
|
|
.on("changed", function(log){
|
|
});
|
|
|
|
// unsubscribes the subscription
|
|
subscription.unsubscribe(function(error, success){
|
|
if(success)
|
|
console.log('Successfully unsubscribed!');
|
|
});
|