Hardfork.isAtLeast

FRONTIER (0) < HOMESTEAD (1) < DAO (2) < ... < CANCUN (16) < PRAGUE (17)

import { Hardfork, LONDON } from 'tevm'

const fork = Hardfork(config.hardfork)

if (!fork.isAtLeast(LONDON)) {
  throw new Error("EIP-1559 requires London or later")
}

// Safe to use EIP-1559 features

import { Hardfork, SHANGHAI } from 'tevm'

function validateNetworkConfig(clientFork: BrandedHardfork, networkFork: BrandedHardfork) {
  if (!clientFork.isAtLeast(networkFork)) {
    throw new Error(
      `Client must support at least ${Hardfork.toString(networkFork)}, ` +
      `but only supports ${Hardfork.toString(clientFork)}`
    )
  }
}

validateNetworkConfig(SHANGHAI, LONDON)  // OK
validateNetworkConfig(LONDON, SHANGHAI)  // Throws error

import { Hardfork, LONDON, CANCUN } from 'tevm'

function selectTxType(fork: BrandedHardfork): number {
  if (fork.isAtLeast(CANCUN)) {
    return 3  // Blob transaction
  }
  if (fork.isAtLeast(LONDON)) {
    return 2  // EIP-1559
  }
  return 0  // Legacy
}