Neo3 Provider API

The NeoLine extension wallet can expose a Neo N3 provider that follows the NEP-21 IDapiProvider interface.

You can use this provider in your dapp to discover a compatible wallet, inspect provider metadata, call Neo3 methods, and listen for account and network changes.

NOTE

Throughout this documentation, we refer to the selected Neo3 NEP-21 provider instance as provider.

Provider Discovery

NEP-21 providers announce themselves through the Neo.DapiProvider.ready event on window.

let provider;

window.addEventListener('Neo.DapiProvider.ready', (event) => {
  if (event.detail.provider.name === 'NeoLine') {
    provider = event.detail.provider;
  }
});

If you want to proactively request a provider, dispatch Neo.DapiProvider.request with the dAPI version you expect:

window.dispatchEvent(new Event('Neo.DapiProvider.request'));

Properties

An NEP-21 provider exposes the following properties:

Property	Type	Description
name	string	Provider name.
version	string	Provider version.
dapiVersion	string	dAPI version. For NEP-21 this should currently be 1.0.
compatibility	string[]	Supported standards, for example ["NEP-11", "NEP-17", "NEP-21"].
connected	boolean	Whether the wallet is currently connected to the dapp.
network	number	Current Neo N3 network magic number.
supportedNetworks	number[]	Networks supported by the provider.
icon	string	Provider icon URL, the scheme of the URL should be either "https" or "data".
website	string	Provider website.
extra	any	Additional provider-specific metadata.

Example

console.log(provider.name);
console.log(provider.dapiVersion);
console.log(provider.network);
console.log(provider.compatibility);

Methods

Neo3 provider methods

The Neo3 provider exposes standardized NEP-21 provider methods such as:

• authenticate

• getAccounts

• pickAddress

• getBalance

• send

• call

• invoke

• makeTransaction

• sign

• signMessage

• relay

• getBlock

• getBlockCount

• getTransaction

• getApplicationLog

• getStorage

• getTokenInfo

The following is an example of using authenticate():

provider
  .authenticate({
    action: "Authentication",
    grant_type: "Signature",
    allowed_algorithms: ["ECDSA-P256"],
    domain: "127.0.0.1",
    networks: [860833102],
    nonce: "1844674407370955161",
    timestamp: 1710000000,
  })
  .then((result) => {
    // Returns the NEP-20 authentication response payload.
  })
  .catch((error) => {
    // If the request fails, the Promise rejects with an error.
  });

Events

The NeoLine provider emits events through the standard on() and removeListener() API. The following is an example of listening to the accountchanged event.

You should remove listeners after you are done listening to an event, for example when a React component unmounts.

function handleAccountsChanged(accounts) {
  // Handle new accounts, or lack thereof.
}

provider.on("accountchanged", handleAccountsChanged);

// Later

provider.removeListener("accountchanged", handleAccountsChanged);

accountchanged

provider.on("accountchanged", handler: (accounts: Account[]) => void);

The provider emits this event when the connected account set changes. The event payload is accounts: Account[].

networkchanged

provider.on("networkchanged", handler: (network: number) => void);

The provider emits this event when the currently connected Neo network changes. The event payload is network: number.

Remove event listeners

removeListener

Use removeListener to remove a specific listener from the provider.

provider.on("accountchanged", updateWallet);
provider.on("networkchanged", updateNetwork);

provider.removeListener("accountchanged", updateWallet);
provider.removeListener("networkchanged", updateNetwork);

Errors

All errors returned by the Neo3 provider follow this interface:

interface ProviderError extends Error {
  code: number;
  message: string;
  data?: any;
}

NEP-21 methods reject eagerly. You can use the error code property to determine why the request failed.

Code	Name	Description
10000	UNKNOWN	An unknown error has occurred.
10001	UNSUPPORTED	The requested feature or operation is not supported.
10002	INVALID	The input data is in an invalid format.
10003	NOTFOUND	The requested data does not exist.
10004	FAILED	Contract execution failed.
10005	TIMEOUT	The requested operation timed out.
10006	CANCELED	The requested operation was canceled by the user.
10007	INSUFFICIENT_FUNDS	The request failed because the balance is insufficient.
10008	RPC_ERROR	The RPC server threw an exception.

When code is 10004, providers may include the failed InvocationResult in data.

interface FailedError extends ProviderError {
  code: 10004;
  message: "Contract execution failed";
  data: InvocationResult;
}

Notes

• Network values are Neo N3 magic numbers, such as 860833102 for MainNet and 894710606 for TestNet.

• All callable Neo3 methods are documented in this section of the Neo3 provider API reference.

• authenticate() follows the NEP-20 authentication challenge and response format.