web3-react

Resources

• Documentation for web3-react is available on Gitbook.

• A live demo of web3-react is available on CodeSandbox.

Introduction

web3-react is a drop in solution for building Ethereum dApps in React. Its marquee features are:

• A large and fully extensible collection of Connectors, which manage connectivity with the Ethereum blockchain and user account(s). Connectors can make your dApp compatible with MetaMask, WalletConnect, Infura, Trust, and more.

• A robust web3 management framework which exposes the current account, the current network ID, and an instantiated ethers.js or web3.js instance to your dapp via a React Context.

• A collection of React Hooks that can be used to display ETH and ERC-20 balances, sign messages, send transactions, etc.

• A number of utility functions to format Etherscan links, convert token balances, etc.

Implementations

Projects using web3-react include:

• https://github.com/NoahHydro/snowflake-dashboard
• https://conlan.github.io/compound-liquidator/
• https://uniswap.info

Open a PR to add your project to the list! If you're interested in contributing, check out Contributing-Guidelines.md.

Quickstart

If you want to cut straight to the chase, check out the CodeSandbox demo!

1. Install

Ensure you have an up-to-date react and react-dom version:

yarn add react@latest react-dom@latest

Then, get the npm package:

yarn add web3-react@unstable

2. Setup Connectors

Now, decide how you want users to interact with your dApp. For the vast majority of dApps, this will be with some combination of MetaMask/Infura/WalletConnect. For more details see Connectors.md.

import { MetaMaskConnector, InfuraConnector, WalletConnectConnector } from 'web3-react/connectors'

const connectors = {
  metamask: new MetaMaskConnector(),
  infura: new InfuraConnector({ providerURL: 'https://mainnet.infura.io/v3/<YOUR-API-KEY>' }),
  walletConnect: new WalletConnectConnector({
    bridge: 'https://bridge.walletconnect.org',
    supportedNetworkURLs: { 1: 'https://mainnet.infura.io/v3/<YOUR-API-KEY>' },
    defaultNetwork: 1
  })
}

3. Setup Web3Provider

The next step is to setup a Web3Provider at the root of your dApp. This ensures that children components are able to take advantage of the web3-react context variables.

import React from 'react'
import Web3Provider from 'web3-react'

export default function App () {
  return (
    <Web3Provider
      connectors={...}
      libraryName={...}
      reRendererNames={...}
    >
      ...
    </Web3Provider>
  )
}

Web3Provider takes 4 props:

1. connectors (required): An object mapping connector names to Connectors (see the previous section).

2. libraryName (optional): web3.js or ethers.js, depending on which library you wish to use in your dApp.

3. reRendererNames (optional) strings which with you wish to control specific re-renders of data after, e.g. a transaction confirmation.

4. children (required): The rest of your dApp.

4. Using web3-react

Finally, you're ready to use web3-react!

Recommended - Hooks

The easiest way to use web3-react is with Hooks.

import React from 'react'
import { useWeb3Context } from 'web3-react/hooks'

function MyComponent() {
  const context = useWeb3Context()

  return <p>{context.account}</p>
}

For more details see Hooks.md.

Conditionally Recommended - Render Props

To use web3-react with render props, wrap Components in a Web3Consumer. It takes two props:

1. recreateOnNetworkChange (optional, default true). A flag that controls whether child components are freshly re-initialized upon network changes.

2. recreateOnAccountChange (optional, default true). A flag that controls whether child components are freshly re-initialized upon account changes.

Note: Re-initialization is often the desired behavior, though properly written Hooks may not require these flags to be set.

import React from 'react'
import { Web3Consumer } from 'web3-react'

function AccountComponent({ account }) {
  return <p>{account}</p>
}

function MyComponent() {
  return <Web3Consumer>{context => <AccountComponent account={context.account} />}</Web3Consumer>
}

Note: This pattern will work for arbitrarily deeply nested components. This means that the Web3Consumer doesn't necessarily need to be at the top level of your app. There also won't be performance concerns if you choose to use multiple Web3Consumers at different nesting levels.

Not Recommended - HOCs

If you must, you use web3-react with an HOC. The withWeb3 wrapper's second argument can optionally be the recreate flags from the render props pattern.

import React from 'react'
import { withWeb3 } from 'web3-react'

function MyComponent({ web3 }) {
  const { account } = web3
  return <p>{account}</p>
}

export default withWeb3(MyComponent)

Note: The high-level component which includes your Web3Provider Component cannot be wrapped with withWeb3.

Context

Regardless of how you inject the context, it looks like:

{
  active: boolean
  connectorName?: string
  library?: Library
  networkId?: number
  account?: string | null
  error: Error | null

  setConnector: Function
  setFirstValidConnector: Function
  unsetConnector: Function

  reRenderers: IReRendererState
  forceReRender: Function
}

Variables

• active: A flag for whether web3-react has been initialized.
• connectorName: The name of the currently active connector
• library: A web3.js or ethers.js instance instantiated with the current web3 provider.
• networkId: The current active network ID.
• account: The current active account.
• error: A global error if one exists.

Manager Functions

• setConnector(connectorName): Activates a connector.
• setFirstValidConnector(connectorName): Tries to activate each connector in turn.
• unsetConnector(): Resets the currently active connector.

Renderers

These variables/functions facilitate the re-rendering of specific data. For example, a user's balance can change over time.

import { useEffect } from 'react'
import { useWeb3Context } from 'web3-react/hooks'

const reRendererNames = ['MyReRenderer']
// assume this array was passed to the Web3Provider...

function MyComponent() {
  const context = useWeb3Context()

  useEffect(() => {
    // run code here that should run again when calling context.forceReRender('MyReRenderer')
  }, [context.reRenderers.MyReRenderer])

  ...
}

• reRenderers: An object, where the keys are the reRendererNames passed into the Web3Provider and the values force re-renders of specific data when included in useEffect hook updaters.
• forceReRender(reRendererName): A function that triggers a global re-render of the reRendererName.

Utility Functions

Documentation for the utility functions exported by web3-react can be found in Utilities.md.

Hooks

Documentation for the hooks exported by web3-react can be found in Hooks.md.

Notes

Prior art for web3-react includes:

• A pure Javascript implementation with some of the same goals: web3-webpacked.

• A non-Hooks port of web3-webpacked to React that had some problems: web3-webpacked-react.

• A React library with some of the same goals but that uses the deprecated React Context API and not Hooks: react-web3.