Provider API

OneKey Browser Extension injects a global API into websites visited by its users at window.$onekey.ethereum. This API allows websites to request users' Ethereum accounts, read data from blockchains the user is connected to, and suggest that the user sign messages and transactions. The presence of the provider object indicates an Ethereum user.

The Ethereum JavaScript provider API is specified by EIP-1193. For modern applications, it is highly recommended to use the EIP-6963 standard for discovering multiple wallet providers, which avoids conflicts between different browser extensions.

Provider Detection

To ensure compatibility and a smooth user experience in a multi-wallet environment, it is highly recommended to detect providers using the EIP-6963 standard.

Recommended: EIP-6963 for Multi-Wallet Support

OneKey fully supports EIP-6963, which allows dApps to discover multiple installed wallet providers without conflicts. This is the modern, recommended approach for all dApps.

// This code snippet demonstrates how to listen for announced providers
// and store them for your dApp to use.

let onekeyProvider = null;

const onAnnounceProvider = (event) => {
  // The event.detail contains the provider info and the provider object itself.
  // event.detail = { info: { uuid, name, icon, rdns }, provider }
  if (event.detail.info.name === 'OneKey') {
    onekeyProvider = event.detail.provider;
  }
  // You can also store all providers in an array to let users choose.
};

// Listen for the announcement event from all wallets
window.addEventListener('eip6963:announceProvider', onAnnounceProvider);

// It's also good practice to dispatch a request event to prompt wallets
// that may have loaded after the initial page load.
window.dispatchEvent(new Event('eip6963:requestProvider'));

// After a short delay, you can check if the onekeyProvider was found.
setTimeout(() => {
  if (onekeyProvider) {
    startApp(onekeyProvider);
  } else {
    console.log('OneKey Wallet not found. Please install it from onekey.so/download');
  }
}, 500);

Legacy Detection & Provider Objects

For compatibility with older dApps, OneKey also injects its provider into window.ethereum.

  • window.ethereum: This is the commonly used provider object. However, if a user has multiple wallets installed, this variable can be overwritten, leading to conflicts. OneKey injects here to maximize compatibility.

  • window.$onekey.ethereum: To avoid conflicts, OneKey also provides its provider via this private, namespaced variable. This ensures a dApp can specifically target OneKey if needed, though using EIP-6963 is preferred.

Basic Usage

For any non-trivial Ethereum web application (dApp) to work, you will need to accomplish three fundamental tasks:

  1. Detect an Ethereum Provider: You must first find out if the user has a wallet like OneKey installed. The recommended way to do this is by using the EIP-6963 standard, as detailed in the Provider Detection section above.

  2. Access User Accounts: Once a provider is detected, you need to request permission to view the user's accounts. This is almost always done by calling the eth_requestAccounts method on the provider object.

  3. Monitor Network Changes: The user can switch between different networks (like Ethereum Mainnet and Sepolia) at any time. Your dApp must listen for the chainChanged event to stay aware of the currently connected network.

The provider object is the essential tool for building a full-featured Web3 application. While you can use the provider API directly for all interactions, many developers prefer using a convenience library to simplify development. We recommend robust, community-vetted libraries like ethers.js or viem, which provide higher-level abstractions and utilities.

Chain IDs

These are the IDs of the Ethereum chains that OneKey supports by default. Visit chainlist.org for a comprehensive list.

Hex
Decimal
Network
Status

0x1

1

Ethereum Main Network

Live

0x38

56

Binance Smart Chain (Mainnet)

Live

0x80

128

Huobi Eco Chain (Mainnet)

Live

0x89

137

Polygon (Matic) Mainnet

Live

0xfa

250

Fantom Main Network

Live

0xaa36a7

11155111

Sepolia Testnet

Active

Methods

Once you have obtained a provider object (e.g., via EIP-6963), you can use the following EIP-1193 methods to interact with the user's wallet.

eth_requestAccounts

Use eth_requestAccounts to request one or more accounts from the user's wallet. Calling this will typically prompt the user with a connection request.

try {
  const accounts = await window.$onekey.ethereum.request({ method: 'eth_requestAccounts' });
  // handle accounts
} catch (error) {
  // handle error, e.g., user rejected request
}

window.$onekey.ethereum.isConnected()

Tip Note that this method has nothing to do with the user's accounts. You may often encounter the word "connected" in reference to whether a web3 site can access the user's accounts. In the provider interface, however, "connected" and "disconnected" refer to whether the provider can make RPC requests to the current chain.

window.$onekey.ethereum.isConnected(): boolean;

Returns true if the provider is connected to the current chain, and false otherwise.

If the provider is not connected, the page will have to be reloaded in order for connection to be re-established. Please see the connect and disconnect events for more information.

window.$onekey.ethereum.request(args)

interface RequestArguments {
  method: string;
  params?: unknown[] | object;
}

window.$onekey.ethereum.request(args: RequestArguments): Promise<unknown>;

Use request to submit RPC requests to Ethereum via OneKey Browser Extension. It returns a Promise that resolves to the result of the RPC method call.

The params and return value will vary by RPC method. In practice, if a method has any params, they are almost always of type Array<any>.

If the request fails for any reason, the Promise will reject with an Ethereum RPC Error.

OneKey Browser Extension supports most standardized Ethereum RPC methods, in addition to a number of methods that may not be supported by other wallets.

See the OneKey Browser Extension RPC API documentation for details.

Example

const params = [  
    {    
        from: '0xb60e8dd61c5d32be8058bb8eb970870f0java7233155',    
        to: '0xd46e8dd67c5d32be8058bb8eb970870f07244567',    
        gas: '0x76c0', // 30400    
        gasPrice: '0x9184e72a000', // 10000000000000    
        value: '0x9184e72a', // 2441406250    
        data: '0xd46e8dd67c5d32be8d46e8dd67c5d32be8058bb8eb970870f072445675058bb8eb970870f072445675',  
     },
 ];

window.$onekey.ethereum.request({    
    method: 'eth_sendTransaction',    
    params,  
}).then((result) => {    
    // The result varies by by RPC method.    
    // For example, this method will return a transaction hash hexadecimal string on success.  
    })  
    .catch((error) => {    
        // If the request fails, the Promise will reject with an error.  
    });

Events

The OneKey Browser Extension provider implements the Node.js EventEmitter API. This section details the events emitted via that API.

There are innumerable EventEmitter guides elsewhere, but you can listen for events like this:

window.$onekey.ethereum.on('accountsChanged', (accounts) => {
  // Handle the new accounts, or lack thereof.
  // "accounts" will always be an array, but it can be empty.
});

window.$onekey.ethereum.on('chainChanged', (chainId) => {
  // Handle the new chain.
  // Correctly handling chain changes can be complicated.
  // We recommend reloading the page unless you have good reason not to.
  window.location.reload();
});

connect

interface ConnectInfo {
  chainId: string;
}

window.$onekey.ethereum.on('connect', handler: (connectInfo: ConnectInfo) => void);

The OneKey Browser Extension provider emits this event when it first becomes able to submit RPC requests to a chain.

We recommend using a connect event handler and the window.$onekey.ethereum.isConnected() method in order to determine when/if the provider is connected.

disconnect

window.$onekey.ethereum.on('disconnect', handler: (error: ProviderRpcError) => void);

The OneKey provider emits this event if it becomes unable to submit RPC requests to any chain. In general, this will only happen due to network connectivity issues or some unforeseen error.

Once disconnect has been emitted, the provider will not accept any new requests until the connection to the chain has been re-established, which requires reloading the page. You can also use the window.$onekey.ethereum.isConnected() method to determine if the provider is disconnected.

accountsChanged

window.$onekey.ethereum.on('accountsChanged', handler: (accounts: Array<string>) => void);

The OneKey provider emits this event whenever the return value of the eth_accounts RPC method changes. eth_accounts returns an array that is either empty or contains a single account address. The returned address, if any, is the address of the most recently used account that the caller is permitted to access. Callers are identified by their URL origin, which means that all sites with the same origin share the same permissions.

This means that accountsChanged will be emitted whenever the user's exposed account address changes.

Tip We plan to allow the eth_accounts array to be able to contain multiple addresses in the near future.

chainChanged

Tip See the Chain IDs section for OneKey Browser Extension's default chains and their chain IDs.

window.$onekey.ethereum.on('chainChanged', handler: (chainId: string) => void);

The OneKey Browser Extension provider emits this event when the currently connected chain changes.

All RPC requests are submitted to the currently connected chain. Therefore, it's critical to keep track of the current chain ID by listening for this event.

A common way to handle this is to reload the page:

window.$onekey.ethereum.on('chainChanged', (_chainId) => window.location.reload());

message

interface ProviderMessage {
  type: string;
  data: unknown;
}

window.$onekey.ethereum.on('message', handler: (message: ProviderMessage) => void);

The OneKey provider emits this event when it receives some message that the consumer should be notified of. The kind of message is identified by the type string.

RPC subscription updates are a common use case for the message event. For example, if you create a subscription using eth_subscribe, each subscription update will be emitted as a message event with a type of eth_subscription.

Errors

All errors thrown or returned by the OneKey provider follow this interface:

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

The window.$onekey.ethereum.request(args) method throws errors eagerly. You can often use the code property to determine why the request failed.

Common codes and their meaning include:

  • 4001: The request was rejected by the user.

  • -32602: The parameters were invalid.

  • -32603: Internal error.

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

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