_section: Provider @<Provider>

Explain what a provider is...


_subsection: Accounts Methods  @<Provider--account-methods>

_property: provider.getBalance(address [ , blockTag = latest ]) => Promise<[[BigNumber]]>  @<Provider-getBalance> @SRC<providers/base-provider>
Returns the balance of //address// as of the //blockTag// block height.

_property: provider.getCode(address [ , blockTag = latest ]) => Promise<string<[[DataHexString]]>>  @<Provider-getCode> @SRC<providers/base-provider>
Returns the contract code of //address// as of the //blockTag// block height. If there is
no contract currently deployed, the result is ``0x``.

_property: provider.getStorageAt(addr, pos [ , blockTag = latest ]) => Promise<string<[[DataHexString]]>>  @<Provider-getStorageAt> @SRC<providers/base-provider>
Returns the ``Bytes32`` value of the position //pos// at address //addr//, as of the //blockTag//.

_property: provider.getTransactionCount(address [ , blockTag = latest ]) => Promise<number>  @<Provider-getTransactionCount> @SRC<providers/base-provider>
Returns the number of transactions //address// has ever **sent**, as of //blockTag//.
This value is required to be the nonce for the next transaction from //address//
sent to the network.

_code: Account Examples @lang<javascript>

// Get the balance for an account...
provider.getBalance("ricmoo.firefly.eth");
//!

// Get the code for a contract...
provider.getCode("registrar.firefly.eth");
//!

// Get the storage value at position 0...
provider.getStorageAt("registrar.firefly.eth", 0)
//!

// Get transaction count of an account...
provider.getTransactionCount("ricmoo.firefly.eth");
//!


_subsection: Blocks Methods  @<Provider--block-methods>

_property: provider.getBlock(block) => Promise<[[providers-Block]]>  @<Provider-getBlock> @SRC<providers/base-provider>
Get the //block// from the network, where the ``result.transactions`` is a list
of transaction hashes.

_property: provider.getBlockWithTransactions(block) => Promise<[[providers-BlockWithTransactions]]>  @<Provider-getBlockWithTransactions> @SRC<providers/base-provider>
Get the //block// from the network, where the ``result.transactions`` is
an Array of [[providers-TransactionResponse]] objects.

_code: Block Examples @lang<javascript>

provider.getBlock(100004)
//!

provider.getBlockWithTransactions(100004)
//!

_subsection: Ethereum Naming Service (ENS) Methods @<Provider--ens-methods>

The [Ethereum Naming Service](link-ens) (ENS) allows a short and
easy-to-remember ENS Name to be attached to any set of keys
and values.

One of the most common uses for this is to use a simple name to
refer to an [Ethereum Address](address).

In the ethers API, nearly anywhere that accepts an address, an
ENS name may be used instead, which can simplify code and make
reading and debugging much simpler.

The provider offers some basic operations to help resolve and
work with ENS names.

_property: provider.lookupAddress(address) => Promise<string>  @<Provider-lookupAddress> @SRC<providers/base-provider>
Performs a reverse lookup of the //address// in ENS using the
//Reverse Registrar//.  If the name does not exist, or the
forward lookup does not match, ``null`` is returned.

_property: provider.resolveName(name) => Promise<string<[Address](address)>>  @<Provider-ResolveName> @SRC<providers/base-provider>
Looks up the address of //name//. If the name is not owned, or
does not have a //Resolver// configured, or the //Resolver// does
not have an address configured, ``null`` is returned.

_code: ENS Examples @lang<javascript>

// Reverse lookup of an ENS by address...
provider.lookupAddress("0x6fC21092DA55B392b045eD78F4732bff3C580e2c");
//!

// Lookup an address of an ENS name...
provider.resolveName("ricmoo.firefly.eth");
//!


_subsection: Logs Methods  @<Provider--log-methods>

_property: provider.getLogs(filter) => Promise<Array<[[providers-Log]]>>  @<Provider-getLogs> @SRC<providers/base-provider>
Returns the Array of [[providers-Log]] matching the //filter//.

Keep in mind that many backends will discard old events, and that requests
which are too broad may get dropped as they require too many resources to
execute the query.


_subsection: Network Status Methods  @<Provider--network-methods>

_property: provider.getNetwork() => Promise<[[providers-Network]]>  @<Provider-getNetwork> @SRC<providers/base-provider:method.BaseProvider.getNetwork>
Returns the [[providers-Network]] this Provider is connected to.

_property: provider.getBlockNumber() => Promise<number>  @<Provider-getBlockNumber> @SRC<providers/base-provider>
Returns the block number (or height) of the most recently mined block.

_property: provider.getGasPrice() => Promise<[[BigNumber]]>  @<Provider-getGasPrice> @SRC<providers/base-provider>
Returns a //best guess// of the [[gas-price]] to use in a transaction.

_code: Network Status Examples @lang<javascript>

// The network information
provider.getNetwork()
// <hide>
//!
network = utils.shallowCopy(_)
delete network._defaultProvider
network
// </hide>
//!

// The current block number
provider.getBlockNumber()
//!

// Get the current suggested gas price (in wei)...
gasPrice = await provider.getGasPrice()
//! async gasPrice

// ...often this gas price is easier to understand or
// display to the user in gwei (giga-wei, or 1e9 wei)
utils.formatUnits(gasPrice, "gwei")
//!


_subsection: Transactions Methods  @<Provider--transaction-methods>

_property: provider.call(transaction [ , blockTag = latest ]) => Promise<string<[[DataHexString]]>>  @<Provider-call> @SRC<providers/base-provider>
Returns the result of executing the //transaction//, using //call//. A call
does not require any ether, but cannot change any state. This is useful
for calling gettings on Contracts.

_property: provider.estimateGas(transaction) => Promise<[[BigNumber]]>  @<Provider-estimateGas> @SRC<providers/base-provider>
Returns an estimate of the amount of gas that would be required to submit //transaction//
to the network.

An estimate may not be accurate since there could be another transaction
on the network that was not accounted for, but after being mined affected
relevant state.

_property: provider.sendTransaction(transaction) => Promise<[[providers-TransactionResponse]]>  @<Provider-sendTransaction> @SRC<providers/base-provider>
Submits //transaction// to the network to be mined. The //transaction// **must** be signed,
and be valid (i.e. the nonce is correct and the account has sufficient balance to pay
for the transaction).

_property: provider.waitForTransaction(hash [ , confirms = 1 [ , timeout ] ]) => Promise<[TxReceipt](providers-TransactionReceipt)>  @<Provider-waitForTransaction> @SRC<providers/base-provider>
Returns a Promise which will not resolve until //transactionHash// is mined.


_subsection: Event Emitter Methods @<Provider--event-methods>

Explain events here...

_property: provider.on(eventName, listener) => this  @<Provider-on> @SRC<providers/base-provider>
Add a //listener// to be triggered for each //eventName//.

_property: provider.once(eventName, listener) => this  @<Provider-once> @SRC<providers/base-provider>
Add a //listener// to be triggered for only the next //eventName//,
at which time it be removed.

_property: provider.emit(eventName, ...args) => boolean  @<Provider-emit> @SRC<providers/base-provider>
Notify all listeners of //eventName//, passing //args// to each listener. This
is generally only used internally.

_property: provider.off(eventName [ , listener ]) => this  @<Provider-off> @SRC<providers/base-provider>
Remove a //listener// for //eventName//. If no //listener// is provided,
all listeners for //eventName// are removed.

_property: provider.removeAllListeners([ eventName ]) => this  @<Provider-removeAllListeners> @SRC<providers/base-provider>
Remove all the listeners for //eventName//. If no //eventName// is provided,
**all** events are removed.

_property: provider.listenerCount([ eventName ]) => number  @<Provider-listenerCount> @SRC<providers/base-provider>
Returns the number of listeners for //eventName//. If no //eventName// is
provided, the total number of listeners is returned.

_property: provider.listeners(eventName) => Array<Listener>  @<Provider-listeners> @SRC<providers/base-provider>
Returns the list of Listeners for //eventName//.


_heading: Events  @<Provider--events>

Any of the following may be used as the //eventName// in the above methods.

_definition: **Log Filter**

A filter is an object, representing a contract log Filter, which has the optional
properties ``address`` (the source contract) and ``topics`` (a topic-set to match).

If ``address`` is unspecified, the filter matches any contract address.

See events for more information on how to specify topic-sets.

_definition: **Topic-Set Filter**

The value of a **Topic-Set Filter** is a array of Topic-Sets.

This event is identical to a //Log Filter// with the address omitted (i.e. from
any contract).

_definition: **Transaction Filter**

The value of a **Transaction Filter** is any transaction hash.

This event is emitted on every block that is part of a chain that
includes the given mined transaction. It is much more common that the
[once](Provider-once) method is used than the [on](Provider-on) method.

_null:

In addition to transaction and filter events, there are several named
events.

_table: Named Provider Events @style<full>

$Block:    emitted when a new block is mined
$Error:    emitted on any error
$Pending:  emitted when a new transaction enters the memory pool; only
           certain providers offer this event and may require
           running your own node for reliable results
$WillPoll: emitted prior to a polling loop is about to begin;
           //(very rarely used by most developers)//
$DidPoll:  emitted after all events from a polling loop are emitted;
           //(very rarely used by most developers)//
$Poll:     emitted during each poll cycle after `blockNumber` is updated
           (if changed) and before any other events (if any) are emitted
           during the poll loop;
           //(very rarely used by most developers)//
$Debug:    each Provider may use this to emit useful debugging information
           and the format is up to the developer;
           //(very rarely used by most developers)//

|   **Event Name**    |  **Arguments**                   <|   **Description**  <<<|
|    ``"block"``      |   //blockNumber//                <| $Block             <<<|
|    ``"error"``      |   //error//                      <| $Error             <<<|
|    ``"pending"``    |   //pendingTransaction//         <| $Pending           <<<|
|    ``"willPoll"``   |   //pollId//                     <| $WillPoll          <<<|
|    ``"poll"``       |   //pollId//, //blockNumber//    <| $Poll              <<<|
|    ``"didPoll"``    |   //pollId//                     <| $DidPoll           <<<|
|    ``"debug"``      |   provider dependent             <| $Debug             <<<|


_code: Events Example @lang<javascript>

// <hide>
const txHash = utils.id("dummy-data");
const myAddress = ethers.constants.HashZero;
const myOtherAddress = ethers.constants.HashZero;
// </hide>

provider.on("block", (blockNumber) => {
    // Emitted on every block change
})


provider.once(txHash, (transaction) => {
    // Emitted when the transaction has been mined
})


// This filter could also be generated with the Contract or
// Interface API. If address is not specified, any address
// matches and if topics is not specified, any log matches
filter = {
    address: "dai.tokens.ethers.eth",
    topics: [
        utils.id("Transfer(address,address,uint256)")
    ]
}
provider.on(filter, (log, event) => {
    // Emitted whenever a DAI token transfer occurs
})


// Notice this is an array of topic-sets and is identical to
// using a filter with no address (i.e. match any address)
topicSets = [
    utils.id("Transfer(address,address,uint256)"),
    null,
    [
        myAddress,
        myOtherAddress
    ]
]
provider.on(topicSets, (log, event) => {
    // Emitted any token is sent TO either address
})


provider.on("pending", (tx) => {
    // Emitted when any new pending transaction is noticed
});


provider.on("error", (tx) => {
    // Emitted when any error occurs
});

// <hide>
// Make sure our documentation builds without waiting forever
provider.removeAllListeners()
// </hide>

_subsection: Inspection Methods  @<Provider--inspection-methods>

_property: Provider.isProvider(object) => boolean  @<Provider-isProvider> @SRC<abstract-provider>
Returns true if and only if //object// is a Provider.