Hardfork.isAtLeast

Check if hardfork is at least a target version (greater than or equal)

Try it Live

Run Hardfork examples in the interactive playground

Chronological Ordering

Hardforks are ordered chronologically by deployment date:

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

Comparison uses array index lookup, making it O(1) constant time.

Usage Patterns

Feature Gating

Check minimum version requirements:

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

Network Configuration

Validate network compatibility:

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

Transaction Type Selection

Select appropriate transaction format:

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
}

EIP References

Common minimum version checks:

Feature	Minimum Version	EIP
EIP-1559 base fee	London	EIP-1559
PUSH0 opcode	Shanghai	EIP-3855
Blob transactions	Cancun	EIP-4844
Transient storage	Cancun	EIP-1153
Proof of Stake	Merge	EIP-3675

Performance

Time Complexity: O(1) - Array index comparison

Typical Time: ~10-20ns per call

See Also

• isBefore - Check if strictly less than
• isAfter - Check if strictly greater than
• compare - Three-way comparison
• gte - Alias for isAtLeast