​

Quickstart

It should take less than 5 minutes to get going with Blocknative Onboard.

Create a Blocknative Account

Go to the Account Dashboard at https://explorer.blocknative.com/account and setup an account with an email address. You will receive an email to confirm your account.

Create your API Key

On the Account Dashboard at https://explorer.blocknative.com/account, create an API key with your choice of name or use/rename the Default Key. Consider using different API keys for development, staging, and production releases.

Install the widget using npm

npm install bnc-onboard

Initialize the Library

Use the minimum required config. There are more options available as detailed in the initialization section.

import Onboard from 'bnc-onboard'
import Web3 from 'web3'
​
let web3;
​
const onboard = Onboard({
  dappId: apiKey,       // [String] The API key created by step one above
  networkId: networkId  // [Integer] The Ethereum network ID your Dapp uses.
  subscriptions: {
    wallet: wallet => {
       web3 = new Web3(wallet.provider)
    }
  }
});
​

The wallet subscription function will be called when the user selects a wallet so you can instantiate web3 with the selected provider.

Onboard User

Ask the user to select a wallet and then check wallet is ready to transact.

await onboard.walletSelect();
await onboard.walletCheck();

And you are live!

Screencasts

See the above Quickstart guide in a screencast:

For a deeper dive with additional wallets that builds on the Quick Start, see this screencast:

Example Code

For an example of a basic React demo integration of both Onboard.js and Notify.js, checkout the GitHub repo: https://github.com/blocknative/onboard-notify-react​

and the live demo:

​https://reactdemo.blocknative.com/ ​

Initialization

Options

const options = {
  dappId: String,
  networkId: Number,
  networkName: String,
  darkMode: Boolean,
  blockPollingInterval: Number,
  subscriptions: {
    address: Function, 
    network: Function,
    balance: Function,
    wallet: Function
  },
  walletSelect: {
    heading: String,
    description: String,
    explanation: String,
    wallets: Array,
    agreement: {
      version: String,
      termsUrl: String,
      privacyUrl: String
    }
  },
  walletCheck: Array
}

dappId - [optional]

Your unique apiKey that identifies your application. You can generate a dappId by visiting the Blocknative account page and create a free account. The dappid enables Onboard to use Blocknative notification services to efficiently maintain address balance state. This is not required to use Onboard to connect wallets to Dapps. It is required to efficiently get an up to date wallet balance value via the balance subscription or getState() calls.

networkId - [required]

The Ethereum network id that your application runs on. The following values are valid:

• 1 Main Network

• 3 Ropsten Test Network

• 4 Rinkeby Test Network

• 5 Goerli Test Network

• 42 Kovan Test Network

• 100 xDai POA Network

networkName - [optional]

This option allows one to specify a custom network name for all non-supported networks (see networkId above for supported networks). For instance, if you set networkId: 56 for Binance smart chain and the user is connected to a different network, the wallet select modal will show local as the network to switch to. But if you specify networkName: "Binance Mainnet" then this will display instead of local.

darkMode - [optional] - Default: false

Opt for the Dark color scheme or not.

blockPollingInterval - [optional] - Default: 4000

Change the rate at which blocks are polled by provider, default is set to 4 seconds.

hideBranding - [optional]

If no dappId is provided, then "Powered by Blocknative" branding will be displayed on all modals. You can choose to hide the branding by setting hideBranding: true. If you have included a dappId then the branding will be hidden by default. If you would like the branding to display when including a dappId then set hideBranding: false.

subscriptions - [optional]

An object of callback functions that get called whenever the corresponding value changes. Use these callbacks to sync your UI or to store the values for use elsewhere in your code. Valid parameters to register callbacks for are:

• address - called with the user's current address [string]

• network - called with the user's current network id [number]

• balance - called with the user's current balance [string]

• wallet - called with the user's current wallet [object: { provider, name, instance }]

walletSelect - [optional]

A object that defines how the wallet select screen will render using the following parameters:

• heading - [optional] : A string that will be the wallet select modal heading

• description - [optional] : A string that will be the wallet select modal description

• explanation - [optional] : A string that will be included in the "What is a Wallet" section

• wallets - [optional] : An array of wallet modules or wallet initialization objects that the user can select from

• agreement - [optional]: An object containing properties for use with terms of service agreement

  • version - The current version of the terms that the user needs to agree to. When this value is updated the user's agreement is invalidated and they must re-agree upon next usage.

  • termsUrl - [optional]: A string that will be used for the terms of service url that a user can agree to before using onboard

  • privacyUrl - [optional]: A string that will be used for the privacy policy url that a user can agree to before using onboard

If not provided, then the default heading and description and wallets that don't require initialization will be included for you.

walletCheck - [optional]

An array of wallet check modules or wallet check initialization objects that will be used to check if the user is ready to transact.

Initialize Onboard

To initialize Onboard, simply import the library and call it with your initializationOptions:

import Onboard from 'bnc-onboard'
​
const initializationOptions = {
    // ..... options here
}
​
const onboard = Onboard(initializationOptions)

The return value will be the initialized onboard library which contains the API functions below.

Local Networks

If you are using a local network for testing, you can ensure that the onboarding checks work correctly by setting the networkId for that local network to a number that is not taken by other valid networks. If you are using the ganache-cli for instance, you can set the networkId via the -i flag:

ganache-cli -i 35

This will set the Ganache networkId to 35

Then in your Onboard config, also set the networkId property to the same value:

const onboard = Onboard({
  networkId: 35,
  // ...other config options
})

API

walletSelect

When you are ready to get a user to select a wallet and connect it to your Dapp, you can call the walletSelect function to display the wallet select modal:

const walletSelected = await onboard.walletSelect()
// returns a Promise that:
// resolves with true if the user selected a wallet
// resolves with false if the user exited from the wallet select modal

This function will show a modal that displays buttons for all of the wallets that you initialized onboard with. It will guide the user through the process of connecting to the wallet that they select. Once the process is successful the function will resolve with true. This means that the provider subscription will have been called with the provider of the selected wallet and you can go ahead and instantiate your web3 library with the provider and also instantiate your contracts.

The walletSelect function can also be called with a autoSelectWallet string. If the string passed in is a valid walletName, then Onboard will automatically select that wallet for the user. This enables saving the previously selected wallet in localStorage and automatically selecting it for the user when they next visit your Dapp.

walletCheck

Once a wallet is selected, you will want to make sure that the user's wallet is prepared and ready to transact by calling the walletCheck function:

const readyToTransact = await onboard.walletCheck()
// returns a Promise that:
// resolves with true if user is ready to transact
// resolves with false if user exited before completing all wallet checks

This function will run through the walletCheck modules that were passed in via initialization sequentially, making sure the user has passed the condition contained in each module and eventually resolves with true if the user completed the sequence. This means that the user is ready to transact. This function is useful to call before every transaction to make sure that nothing has changed since the last time it was called.

walletReset

You may want to reset all of Onboard's internal wallet state and also disconnect from any active SDK instances when a user logs out of your app. You can call the walletReset function to do this easily.

// user wants to log out of session and the wallet state needs to be reset...
onboard.walletReset()
// this method is synchronous and returns undefined

accountSelect

If you want to show the account select modal for hardware wallets at any time you can call the accountSelect function. For example you could display a button that allows the user switch accounts:

<button onclick="onboard.accountSelect()">Switch Account</button>

getState

This function will give you the current state of the user:

const currentState = onboard.getState()
console.log(currentState)
// {
//    address: string
//    network: number
//    balance: string
//    wallet: Wallet
//    mobileDevice: boolean
//    appNetworkId: number
// }

config

You can update some configuration parameters by passing a config object in to the config function:

onboard.config({ darkMode: true, networkId: 4 })

Available parameters that you can update are:

• darkMode - [boolean]

• networkId - [number]

Built-in Modules

Wallet Modules

Initialization:

To initialize the built in wallet modules, an array of wallet initialization objects needs to be passed to the walletSelect.wallets parameter of the Onboard initialization object. The order of the array is the order that the wallets will be displayed. Mobile wallets will be displayed when a user is on a mobile device and desktop wallets are displayed when they are on a desktop device.

Each wallet initialization object has additional optional customization parameters:

• preferred - Boolean Will define whether it is shown at the top of the selection screen. If any of the wallets are set to preferred, then all other wallets that aren't, will be hidden until the user clicks the "Show More" button. If there are no wallets set to preferred, then the first four wallets will be shown and the remaining wallets will be hidden until the show more button is clicked.

• label - String Will over ride the wallet name that is displayed on the button.

• svg - String An svg string that will over ride the icon that is displayed on the button.

• iconSrc - String An alternative to providing the svg string, by providing a url source.

An example configuration that includes all of the supported wallets:

import Onboard from 'bnc-onboard'
​
const FORTMATIC_KEY = "Your Fortmatic key here"
const PORTIS_KEY = "Your Portis key here"
const INFURA_KEY = "Your Infura key here"
const APP_URL = "Your app url here"
const CONTACT_EMAIL = "Your contact email here"
const RPC_URL = "https://<network>.infura.io/v3/<INFURA_KEY>"
const APP_NAME = "Your app name here"
​
const wallets = [
  { walletName: "coinbase", preferred: true },
  { walletName: "trust", preferred: true, rpcUrl: RPC_URL },
  { walletName: "metamask", preferred: true },
  { walletName: "authereum" },
  {
    walletName: 'trezor',
    appUrl: APP_URL,
    email: CONTACT_EMAIL,
    rpcUrl: RPC_URL
  },
  {
    walletName: 'ledger',
    rpcUrl: RPC_URL
  },
  {
    walletName: 'lattice',
    rpcUrl: RPC_URL,
    appName: APP_NAME
  },
  { 
    walletName: 'cobovault',
    rpcUrl: RPC_URL,
    appName: APP_NAME,
  },
  {
    walletName: "fortmatic",
    apiKey: FORTMATIC_KEY,
    preferred: true
  },
  {
    walletName: "portis",
    apiKey: PORTIS_KEY,
    preferred: true,
    label: 'Login with Email'
  },
  {
    walletName: "walletConnect",
    infuraKey: INFURA_KEY
  },
  { walletName: "opera" },
  { walletName: "operaTouch" },
  { walletName: "torus" },
  { walletName: "status" },
  { walletName: "walletLink" rpcUrl: RPC_URL, appName: APP_NAME }
  { walletName: "imToken", rpcUrl: RPC_URL },
  { walletName: "meetone" },
  { walletName: "mykey", rpcUrl: RPC_URL },
  { walletName: "huobiwallet", rpcUrl: RPC_URL },
  { walletName: "hyperpay" },
  { walletName: "wallet.io", rpcUrl: RPC_URL },
  { walletName: "atoken" },
  { walletName: "frame" },
  { walletName: "ownbit" },
  { walletName: "alphawallet" }
]
​
const onboard = Onboard({
  //... other options
  walletSelect: {
     wallets: wallets 
  }
})

The following list of wallet modules are included in Onboard and their initializationObject is listed for each wallet:

Wallets

• metamask

{ walletName: 'metamask' }

• authereum

{ 
  walletName: 'authereum',
  disableNotifications: false // [OPTIONAL]
  rpcUri: '<CUSTOM_RPC_URI>' // [OPTIONAL]
  webUri: '<CUSTOM_WEB_URI>' // [OPTIONAL]
  xsUri: '<CUSTOM_XS_URI>' // [OPTIONAL]
  blockedPopupRedirect: true // [OPTIONAL]
}

• walletConnect

{
  walletName: 'walletConnect',
  infuraKey: 'INFURA_KEY', // your infura id [String][Optional if rpc is provided instead]
  rpc: {
    ['networkId']: '<RPC_ENDPOINT_URL_STRING>'
  }, // [Optional]
  bridge: '<BRIDGE_URL>' // url to a bridge server [String][Optional]
}

• portis

{
  walletName: 'portis',
  apiKey: 'PORTIS_KEY' // your Portis apiKey [String]
}

• fortmatic

{
  walletName: 'fortmatic',
  apiKey: 'FORTMATIC_KEY' // your Fortmatic apiKey [String]
}

• trust

{ walletName: 'trust' }

• coinbase

{ walletName: 'coinbase' }

• opera

{ walletName: 'opera' }

• opera touch

{ walletName: 'operaTouch' }

• status

{ walletName: 'status' }

• torus

For additional details on the Torus options, check out their docs​

{
  walletName: 'torus',
  buttonPosition: String, // [optional]
  modalZIndex: Number, // [optional]
  apiKey: String, // [optional]
  buildEnv: String, // 'production' | 'development' | 'staging' | 'testing' | 'lrc' [optional]
  enableLogging: Boolean, // [optional]
  enabledVerifiers: VerifierStatus, // [optional]
  loginConfig: LoginConfig, // [optional]
  showTorusButton: Boolean, // [optional]
  integrity: IntegrityParams, // [optional]
  whiteLabel: WhiteLabelParams, // [optional]
  loginMethod: String // 'google' | 'facebook' | 'twitch' | 'reddit' | 'discord' |  [optional]
}

• trezor

Trezor requires extra details such as appUrl and email for their manifest​

{
  walletName: 'trezor',
  appUrl: APP_URL, // the url of your app (required for manifest)
  email: CONTACT_EMAIL, // your contact email, (required for manifest)
  rpcUrl: RPC_URL // url to connect to an RPC endpoint (ie infura)
}

• ledger

Ledger has an additional optional LedgerTransport parameter for when you are building an Electron app and need to pass in the node ledger transport module. You can also use this option to pass in whichever Ledger transport that you would like to use based on feature detection (eg. Windows 10 user might need WebUSB transport instead of the default U2F transport).

{
  walletName: 'ledger',
  rpcUrl: RPC_URL // url to connect to an RPC endpoint (ie infura)
  LedgerTransport: TransportNodeHid
}

• lattice

{
  walletName: 'lattice',
  rpcUrl: RPC_URL, // url to connect to an RPC endpoint (ie infura)
  appName: APP_NAME // app name that is displayed on device
}

• cobovault

{
  walletName: 'cobovault',
  rpcUrl: RPC_URL, // url to connect to an RPC endpoint (ie infura)
  appName: APP_NAME // app name that is displayed on device
}

• walletLink

{ 
  walletName: 'walletLink',
  rpcUrl: RPC_URL, // url to connect to an RPC endpoint (ie infura)
  appName: <YOUR_APP_NAME>, // string to label your app 
  appLogoUrl: <YOUR LOGO URL> // string url of your app logo [OPTIONAL]
}

• imToken

{
  walletName: 'imToken',
  rpcUrl: RPC_URL // url to connect to an RPC endpoint (ie infura)[OPTIONAL]
}

• meetone

{ walletName: 'meetone' }

• mykey

{
  walletName: 'mykey',
  rpcUrl: RPC_URL // url to connect to an RPC endpoint (ie infura)[OPTIONAL]
}

• huobiwallet

{
  walletName: 'huobiwallet',
  rpcUrl: RPC_URL // url to connect to an RPC endpoint (ie infura)[OPTIONAL]
}

• hyperpay

{ walletName: 'hyperpay' }

• wallet.io

{ walletName: "wallet.io", rpcUrl: RPC_URL } // url to connect to an RPC endpoint (ie infura)[OPTIONAL]

• atoken

{ walletName: "atoken" }

• frame

{ walletName: "frame" }

• ownbit

{ walletName: "ownbit" }

• alphawallet

{ walletName: "alphawallet" }

​

Wallet Check Modules

Initialization:

To initialize the built in wallet check modules, an array of wallet check initialization objects needs to be passed to the walletCheck parameter of the Onboard initialization object. The order of the array is the order that the checks will be performed.

Each wallet check initialization object has additional optional customization parameters:

• heading - String Will over ride the heading displayed in the wallet check modal.

• description - String Will over ride the description displayed in the wallet check modal.

• icon - String An svg string that will over ride the icon displayed in the wallet check modal.

• button - { text: String, onclick: () => void} An object that defines an extra button's text and onclick function.

• html - String A html string that will be rendered in the modal as html markup underneath the description.

import Onboard from 'bnc-onboard'
​
const walletChecks = [
  { checkName: 'derivationPath' },
  { checkName: 'accounts' },
  { checkName: 'connect' },
  { checkName: 'network' },
  { checkName: 'balance', minimumBalance: '1000000' }
]
​
const onboard = Onboard({
  //... other options
  walletCheck: walletChecks
})

The following wallet check modules are included in Onboard:

• connect: Checks that the Dapp has access to the users' accounts and fires the connect function if the selected wallet has one to prompt the user to allow access.

{ checkName: 'connect' }

• derivationPath: Provides a UI to allow a user to select or input the derivation path they would like to use with their hardware wallet. Note: will only display if the connected wallet is of type "hardware". Note: html and button customization parameters won't work for this module as it needs them itself for correct operation.

{ checkName: 'derivationPath' }

• accounts: Provides a UI to allow a user to select and load accounts on their hardware wallet. Note: will only display if the connected wallet is of type "hardware". Note: html and button customization parameters won't work for this module as it needs them itself for correct operation.

{ checkName: 'accounts' }

• network: Checks that the users' wallet is connected to the network that the modules were initialized with.

{ checkName: 'network' }

• balance: Checks that the users' account has the minimum balance as defined when initialized.

{
  checkName: 'balance',
  minimumBalance: '1000000' // The minimum balance in wei required [String]
}

Creating Custom Modules

Onboard has been built so that custom wallet and wallet check modules can be plugged in to allow for the breadth of different wallets and on-boarding flows that are needed across the web3 ecosystem.

Custom Wallet Modules

A wallet module is an abstraction that allows interoperability between wallets within Onboard.

A wallet module has the following properties:

name - [string][required]

The name of the wallet.

wallet - [function][required]

A function that is called when this wallet is selected. It is called with a helpers object that includes some helper functions that make it easier to create the return object. The helpers object contains the following methods:

• getProviderName - A function that takes a provider as an argument and will return the name of the most common providers.

• createLegacyProviderInterface - A function that takes the provider as an argument and returns a walletInterface. Legacy refers to a provider that has not implemented EIP-1102.

• createModernProviderInterface - A function that takes the provider as an argument and returns a walletInterface. Modern refers to a provider that has implemented EIP-1102. This will work for most providers and is a quick way to create an interface.

• BigNumber - A bignumber.js function for number calculations.

• getNetwork - A function that takes a provider and will make a JSON-RPC call to get the network.

• getAddress - A function that takes a provider and will make a JSON-RPC call to get the address.

• getBalance - A function that takes a provider and will make a JSON-RPC call to get the balance.

The wallet function must return a Promise that resolves to an object that has the following properties:

provider - the JavaScript provider for this wallet. [required]

instance - for SDK wallets instances that are separate from the provider. [optional]

interface - a walletInterface or null if the user's current provider is not this wallet (for extension and mobile wallets). [required]

walletInterface

An abstraction built on top of an Ethereum JavaScript provider allowing interoperability with wallets and providers of any architecture. A valid walletInterface implements the following methods and attributes:

name - The name of the wallet. [string][required]

connect - A function that requests account access and returns a Promise that resolves or rejects once the user confirms or rejects the request. [function][optional]

disconnect - A function to clean up / destroy any instances (mostly for SDK wallets). Will be called when a new wallet has been selected. [function][optional]

loading - A function that returns a Promise that resolves when the wallet has finished loading. This is to show a loading spinner as the wallet popup is loading (mostly for SDK wallets). [function][optional]

address - A stateSyncer object (see below for details). The get function on this stateSyncer must return a string which is the wallet address.

network - A stateSyncer object (see below for details). The get function on this stateSyncer must return a number which is the wallet network id.

balance - A stateSyncer object (see below for details). The get function on this stateSyncer must return a string which is the wallet address balance.

stateSyncer

An object that has either a get function or a onChange function and is used to keep user state in sync. The onChange method is preferred as it doesn't require background polling to keep in sync.

The get function returns a promise that resolves with a value.

The onChange function takes a setState function as an argument and is used to set the state. Often it is needed to use the setState function to set the initial state and then register it to be called every time it changes.

iconSrc - [string][optional]

A source for the wallet logo icon.

iconSrcSet - [string][optional]

A source for the hi-res wallet logo icon.

svg - [string][optional]

A svg element string for the wallet logo icon.

link - [string][optional]

A link to install this wallet (extension and injected provider wallets).

installMessage - [function][optional]

A function that will be called when a user has selected this wallet, but the wallet function did not return a wallet interface. This is generally only needed if this wallet injects the provider via an extension or mobile wallet and the user doesn't have the extension installed or is on the wrong mobile browser. The function will be called with an object that has two properties: currentWallet (the name of the wallet that has been detected by Onboard) and selectedWallet (the name of the selected wallet), and must return a string (that can include html) that instructs the user to install this wallet.

desktop - [boolean][optional]

Whether the wallet is a desktop wallet or not.

mobile - [boolean][optional]

Whether the wallet is a mobile wallet or not.

preferred - [boolean][optional

Whether this wallet will be displayed as a preferred wallet.

Example

import Onboard from 'bnc-onboard'
import SomeSDKWallet from 'some-sdk-wallet'
​
const customExtensionWalletLogo = `
	<svg 
		height="40" 
		viewBox="0 0 40 40" 
		width="40" 
		xmlns="http://www.w3.org/2000/svg"
	>
		<path 
			d="m2744.99995 1155h9.99997" 
			fill="#617bff" 
		/>
	</svg>
`
​
const customSDKWalletLogo = `
	<svg 
		height="40" 
		viewBox="0 0 40 40" 
		width="40" 
		xmlns="http://www.w3.org/2000/svg"
	>
		<path 
			d="m2744.99995 1155h9.99997" 
			fill="#617bff" 
		/>
	</svg>
`
​
// create custom wallet
const customExtensionWallet = {
	name: 'Extension Wallet',
	svg: customExtensionWalletLogo,
	wallet: async helpers => {
		const { createModernProviderInterface } = helpers
		const provider = window.ethereum
		const correctWallet = window.ethereum.currentProvider.isExtensionWallet
​
		return {
			provider,
			interface: correctWallet ? createModernProviderInterface(provider) : null
		}
	},
	link: 'https://some-extension-wallet.io',
	installMessage: wallets => {
		const { currentWallet, selectedWallet } = wallets
		if (currentWallet) {
			return `You have ${currentWallet} installed already but if you would prefer to use ${selectedWallet} instead, then click below to install.`
		}
​
		return `You will need to install ${selectedWallet} to continue. Click below to install.`
	},
	desktop: true
}
​
// create custom wallet
const customSDKWallet = {
	name: 'SDK Wallet',
	svg: customSDKWalletLogo,
	wallet: async helpers => {
		const { createModernProviderInterface } = helpers
		const instance = new SomeSDKWallet({ apiKey: 'sd3d3fwd' })
		const provider = instance.getProvider()
​
		return {
			provider,
			interface: createModernProviderInterface(provider),
			instance
		}
	},
	desktop: true,
	mobile: true
}
​
const defaultWallets = [
	{ walletName: 'metamask' }, 
	{ walletName: 'coinbase' }
]
​
// initialize onboard
const onboard = Onboard({
	//... other options
		walletSelect: {
			wallets: [...defaultWallets, customExtensionWallet, customSDKWallet]
		},
		//... other options
	}
})

Custom Wallet Check Modules

You can create custom onboarding flows by stringing together a sequence of wallet check modules that check that the users' state is correct before moving forward. A wallet check module is a function that gets called with an object which contains the users' current state and either returns a result of undefined if that check has passed or a modalObject if it failed. A wallet check module can also return a Promise that resolves to the check result, allowing asynchronous actions and checks to be a part of your onboarding flow.

A wallet check module will be called with a state object with the following parameters and functions:

address - The users' current address. [string]

network - The users' current network id. [number]

balance - The users' current account balance in wei. [string]

appNetworkId - The networkId that the Dapp is configured to work with. [number]

wallet - The users' wallet object containing the properties: provider, interface, connect, name, loading and instance. [object]

mobileDevice - Whether the user is on a mobile device or not. [boolean]

BigNumber - A bignumber.js function for number calculations. [function]

walletSelect - Call this to switch wallets, will close wallet check dialog and open wallet select dialog. [function]

exit - Call to exit wallet check dialog. [function]

modalObject

The module function then needs to evaluate a condition and then return a result of undefined if the condition has been met or a modalObject if not. The modalObject is an object with the following properties:

heading - The heading for the wallet check modal. [string][required]

description - The description for the wallet check modal. [string][required]

eventCode - An event code that is used for your back-end analytics dashboard. [string][required]

button - A object with an onclick property to register a function to run when the button is clicked, and a text property for the button text [object][optional]

html - A html string that will be rendered in the modal as html markup underneath the description [string][optional]

icon - A icon to be displayed next to the heading. [string][optional]

action - A function to run upon showing the modal that returns a Promise that resolves when finished or rejects with an error. [function][optional]

Example

For a user to interact with your Dapp, they may require a token balance (ie Dai). You could build a module that checks that a user has the required token balance to continue:

import Onboard from 'bnc-onboard'
import ethers from 'ethers'
import erc20 from './erc20'
​
function tokenBalance({ tokenAddress, minimumBalance, tokenName }) {
  let ethersProvider;
  let tokenContract;
​
  return async stateAndHelpers => {
    const {
      wallet: { provider },
      address,
      BigNumber
    } = stateAndHelpers;
​
    if (!tokenContract) {
      ethersProvider = new ethers.providers.Web3Provider(provider);
      tokenContract = new ethers.Contract(tokenAddress, erc20, ethersProvider);
    }
​
    const tokenDecimals = await tokenContract.decimals();
    const divideBy = new BigNumber(10).pow(tokenDecimals);
    const tokenBalanceResult = await tokenContract
      .balanceOf(address)
      .then(res => res.toString());
    const tokenBalance = new BigNumber(tokenBalanceResult).div(divideBy);
​
    if (tokenBalance.lt(minimumBalance)) {
      return {
        heading: `Get Some ${tokenName}`,
        description: `You need to have at least ${minimumBalance} ${tokenName} to interact with this Dapp. Send some more ${tokenName} to this address or switch to another address that has a higher ${tokenName} balance.`,
        eventCode: "tokenBalance",
        icon: `
        	<svg 
        		height="18" 
        		viewBox="0 0 429 695" 
        		width="18" xmlns="http://www.w3.org/2000/svg"
        	>
        		<g 
        			fill="currentColor" 
        			fill-rule="evenodd"
            >
        		 <path d="m0 394 213 126.228516 214-126.228516-214 301z"/>
             <path d="m0 353.962264 213.5-353.962264 213.5 353.962264-213.5 126.037736z"/>
            </g>
           </svg>
        `
      };
    }
  };
}
​
const defaultWalletChecks = [
	{ checkName: 'connect' },
	{ checkName: 'network' },
	{ checkName: 'balance', minimumBalance: '100000' }
]
​
const tokenBalanceCheck = tokenBalance({tokenAddress: '0x6b175474e89094c44da98b954eedeac495271d0f', tokenName: 'Dai', minimumBalance: 5})
​
const onboard = Onboard({
	//... other options
	walletCheck: [...defaultWalletChecks, tokenBalanceCheck]
})

Caching Wallet Selection

You may want to cache the wallet a user has selected previously so that you can automatically select it for them next time they visit your app for a silky smooth user experience. The first step is to store the wallet name in local storage when the user selects a wallet. You can do this by adding some code to your wallet subscription function inside the onboard config:

const config = {
  //... other config options
  subscriptions: {
    wallet: wallet => {
      // store the selected wallet name to be retrieved next time the app loads
      window.localStorage.setItem('selectedWallet', wallet.name)
    }
  }
}
​
const onboard = Onboard(config)

Then you can add code that runs when your app first load, that will retrieve the selectedWallet value from localStorage and then call walletSelect with that value. Onboard will then automatically select it for the user if that wallet is available:

function onLoad() {
  // ... initialize onboard
  
  // get the selectedWallet value from local storage
  const previouslySelectedWallet = window.localStorage.getItem('selectedWallet')
  
  // call wallet select with that value if it exists
  if (previouslySelectedWallet != null) {
    await onboard.walletSelect(previouslySelectedWallet)
  }
}

Customizing CSS