JavaScript ethers fallback provider example

fallbackProvider.js

const { providers } = require('ethers')

async function main() {
  const url1 = 'https://optimism-mainnet.infura.io/v3/84842078b09946638c03157f83405213'
  const url2 = 'https://mainnet.optimism.io'
  const stallTimeout = 2 * 1000
  const options = {
    timeout: 60 * 1000,
    throttleLimit: 1
  }
  const quorum = 1
  const provider1 = new providers.StaticJsonRpcProvider({url: url1, ...options})
  const provider2 = new providers.StaticJsonRpcProvider({url: url2, ...options})
  const provider = new providers.FallbackProvider([
    {
      provider: provider1,
      priority: 2,
      weight: 1,
      stallTimeout
    },
    {
      provider: provider2,
      priority: 1,
      weight: 1,
      stallTimeout
    }
  ], quorum)

  const network = await provider.getNetwork()
  console.log(network)
}

main().catch(console.error)