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:

• Complete support for commonly used web3 providers including MetaMask, Infura, Trezor/Ledger, Fortmatic, WalletConnect, and more.

• A robust framework which exposes an instantiated ethers.js or web3.js instance, the current account and network id, and a variety of helper functions to your dApp via a React Context.

• The ability to write custom, fully featured Connectors to manage every aspect of your dApp's connectivity with the Ethereum blockchain and user account(s).

Quickstart

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

1. Install

Ensure you're using the latest react and react-dom versions (or anything ^18):

yarn add react@latest react-dom@latest

Next, install either ethers.js or web3.js, depending on your preference:

yarn add ethers

yarn add web3

Finally you're ready to use web3-react:

yarn add web3-react@unstable

2. Setup Connectors

Now, you'll need to decide how you want users to interact with your dApp. This is almost always with some combination of MetaMask, Infura, Trezor/Ledger, WalletConnect, etc. For more details on each of these options, see Connectors.md.

import { Connectors } from 'web3-react'
const { MetaMaskConnector, NetworkOnlyConnector } = Connectors

const metaMask = new MetaMaskConnector({ supportedNetworks: [1, 5] })

const infura = new NetworkOnlyConnector({
  providerURL: 'https://mainnet.infura.io/v3/...'
})

const connectors = { metaMask, infura }

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.

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

export default function App () {
  return (
    <Web3Provider
      connectors={...}
      libraryName={'ethers.js'|'web3.js'}
    >
      ...
    </Web3Provider>
  )
}

The Web3Provider takes 2 props:

1. connectors: any (required): An object mapping arbitrary string connector names to Connector objects (see the previous section for more detail).

2. libraryName: string (optional): ethers.js or web3.js, depending on which library you wish to use in your dApp. Passing null will expose the low-level provider object.

4. Activate

Now, you need to decide how/when you would like to activate your Connectors. For all options, please see the manager functions section. The example code below attempts to automatically activate metamask, and falls back to infura.

import React, { useEffect } from 'react'
import { useWeb3Context } from 'web3-react'

// This component must be a child of <App> to have access to the appropriate context
export default function MyComponent () {
  const context = useWeb3Context()

  useEffect(() => {
    context.setFirstValidConnector(['metaMask', 'infura'])
  }, [])

  if (!context.active && !context.error) {
    // loading
    return ...
  } else if (context.error) {
    //error
    return ...
  } else {
    // success
    return ...
  }
}

5. Using web3-react

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

Recommended - Hooks

The easiest way to use web3-react is with the useWeb3Context hook.

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

function MyComponent() {
  const context = useWeb3Context()

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

Conditionally Recommended - Render Props

To use web3-react with render props, wrap Components in a Web3Consumer.

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

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

The component takes 2 props:

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

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

Not Recommended - HOCs

If you must, you can use web3-react with an HOC.

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

function MyComponent({ web3 }) {
  const { account } = web3

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

export default withWeb3(MyComponent)

withWeb3 takes an optional second argument, an object that can set the flags defined above in the render props section.

Note: The Component which includes your Web3Provider Component cannot be wrapped with withWeb3.

Context

Regardless of how you access the web3-react context, it will look like:

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

  setConnector: (connectorName: string, suppressAndThrowErrors?: boolean) => Promise<void>
  setFirstValidConnector: (connectorNames: string[], suppressAndThrowErrors?: boolean) => Promise<void>
  unsetConnector: () => void
  setError: (error: Error, connectorName?: string) => void
}

Variables

• active: A flag indicating whether web3-react currently has an connector set.
• connectorName: The name of the currently active connector.
• connector: The instance of the currently active connector.
• library: An instantiated ethers.js or web3.js instance.
• networkId: The current active network ID.
• account: The current active account if one exists.
• error: The current active error if one exists.

Manager Functions

• setConnector(connectorName: string, suppressAndThrowErrors?: boolean): Activates a connector by name. The second argument is a flag (false by default) that controls whether errors, instead of bubbling up to context.error, are instead thrown by this function.
• setFirstValidConnector(connectorNames: string[], suppressAndThrowErrors: boolean = false): Tries to activate each connector in turn by name. The second argument is a flag (false by default) that controls whether errors, instead of bubbling up to context.error, are instead thrown by this function.
• unsetConnector(): Unsets the currently active connector.
• setError(error: Error, connectorName?: string): Sets context.error, with an optional connector name.

Implementations

Projects using web3-react include:

• https://hydroblockchain.github.io/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.

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 does not use hooks: react-web3.