Ethereum provider API

The NeoLine extension wallet injects an Ethereum provider, as specified by EIP-1193, into the browser at window.NEOLineNeoX.

You can use this provider in your dapp to request users' Ethereum accounts, read on-chain data, and have the user sign messages and transactions.

NOTE

NeoLine supports EIP-6963, You can access the provider API using the selected EIP-6963 provider object. Throughout this documentation, we refer to the selected provider using provider.

let provider;
window.addEventListener('eip6963:announceProvider', (event) => {
  if (event.detail.provider.isNEOLine) {
    provider = event.detail.provider;
  }
});
window.dispatchEvent(new Event('eip6963:requestProvider'));

Properties

isNEOLine

This property is true if the user has NeoLine installed, and false otherwise.

Example

provider.isNEOLine // Or window.NEOLineNeoX.isNEOLine if you don't support EIP-6963.

Methods

request()

This method is used to submit JSON-RPC API requests to Ethereum using NeoLine.

Parameters

An object containing:

• method: string - The JSON-RPC API method name.

• params: array or object - (Optional) Parameters of the RPC method. In practice, if a method has parameters, they're almost always of type array.

Returns

A promise that resolves to the result of the RPC method call. If the request fails, the promise rejects with an error.

Example

The following is an example of using request() to call eth_sendTransaction:

provider // Or window.NEOLineNeoX if you don't support EIP-6963.
  .request({
    method: "eth_sendTransaction",
    params: [
      {
        from: "0xE45e9AdC2B51514849ea5B38dF37d1a65e6D52f5",
        to: "0x7Cd07BCbcCF30d71E768F5228b56d5B7Cc07f674",
        value: "0x3b9aca00", // 1_000_000_000
      },
    ],
  })
  .then((result) => {
    // The result varies by RPC method.
    // For example, this method returns a transaction hash hexadecimal string upon success.
  })
  .catch((error) => {
    // If the request fails, the Promise rejects with an error.
  })

NeoLine Wallet supports many standardized Ethereum RPC methods, including:

• wallet_addEthereumChain

• wallet_switchEthereumChain

• wallet_watchAsset

• personal_sign

• eth_signTypedData_v4

• eth_chainId

• eth_accounts

• eth_requestAccounts

• eth_sendTransaction

• eth_sendRawTransaction

• eth_blockNumber

• eth_call

• eth_estimateGas

• ...

Events

The NeoLine provider emits events using the Node.js EventEmitter API. The following is an example of listening to the accountsChanged event.

You should remove listeners after you're done listening to an event (for example, on component unmount in React).

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

provider // Or window.NEOLineNeoX if you don't support EIP-6963.
  .on("accountsChanged", handleAccountsChanged)

// Later

provider // Or window.NEOLineNeoX if you don't support EIP-6963.
  .removeListener("accountsChanged", handleAccountsChanged)

accountsChanged

provider // Or window.NEOLineNeoX if you don't support EIP-6963.
  .on("accountsChanged", handler: (accounts: string[]) => void);

The provider emits this event when the return value of the eth_accounts RPC method changes. eth_accounts returns either an empty array, or an array that contains the addresses of the accounts the caller is permitted to access with the most recently used account first. Callers are identified by their URL origin, which means that all sites with the same origin share the same permissions.

chainChanged

provider // Or window.NEOLineNeoX if you don't support EIP-6963.
  .on("chainChanged", handler: (chainId: string) => void);

The provider emits this event when the currently connected chain changes. Listen to this event to detect a user's network.

Remove event listeners

removeListener

Use the removeListener method to remove specific event listeners from an EventEmitter object. In the following example removeListener is used to remove the chainChanged and accountsChanged events:

// Use window.NEOLineNeoX instead of provider if EIP-6963 is not supported.

// Add listeners
provider.on("accountsChanged", updateWallet)
provider.on("chainChanged", updateWalletAndAccounts)

// Remove individual listeners
provider.removeListener("accountsChanged", updateWallet)
provider.removeListener("chainChanged", updateWalletAndAccounts)

Errors

All errors returned by the NeoLine provider follow this interface:

interface ProviderRpcError extends Error {
  message: string
  code: number
  data?: unknown
}

The request() provider method throws errors eagerly. You can use the error code property to determine why the request failed. Common codes and their meaning include:

• 4001 - The request is rejected by the user.

• -32602 - The parameters are invalid.

• -32603 - Internal error.

For the complete list of errors, see EIP-1193 and EIP-1474.