feat: lru cache on checksumAddress; note on EIP-1191

.changeset/loud-days-argue.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Added note on EIP-1191 checksum.

.changeset/wet-gorillas-fly.md

@@ -0,0 +1,5 @@
+---
+"viem": patch
+---
+
+Added LRU cache for `checksumAddress`.

site/pages/docs/utilities/getAddress.md

@@ -19,10 +19,6 @@ import { getAddress } from 'viem'
 
 getAddress('0xa5cc3c03994db5b0d9a5eEdD10Cabab0813678ac') // [!code focus:2]
 // '0xa5cc3c03994DB5b0d9A5eEdD10CabaB0813678AC'
-
-// EIP-1191 address
-getAddress('0x27b1fdb04752bbc536007a920d24acb045561c26', 30)
-// '0x27b1FdB04752BBc536007A920D24ACB045561c26'
 ```
 
 ## Returns
@@ -44,3 +40,13 @@ An Ethereum address.
 - **Type:** `number`
 
 The chain ID of the network the address is on. Complies to [EIP-1191](https://eips.ethereum.org/EIPS/eip-1191).
+
+:::warning[Warning]
+EIP-1191 checksum addresses are generally not backwards compatible with 
+the wider Ethereum ecosystem, meaning it will break when validated against 
+an application/tool that relies on EIP-55 checksum encoding (checksum without chainId).
+
+It is highly recommended to not use this feature unless you know what you are doing.
+
+See more: https://github.com/ethereum/EIPs/issues/1121
+:::

src/utils/address/getAddress.ts

@@ -7,17 +7,33 @@ import {
   stringToBytes,
 } from '../encoding/toBytes.js'
 import { type Keccak256ErrorType, keccak256 } from '../hash/keccak256.js'
+import { LruMap } from '../lru.js'
 import { type IsAddressErrorType, isAddress } from './isAddress.js'
 
+export const checksumAddressCache = /*#__PURE__*/ new LruMap<Address>(8192)
+
 export type ChecksumAddressErrorType =
   | Keccak256ErrorType
   | StringToBytesErrorType
   | ErrorType
 
 export function checksumAddress(
   address_: Address,
+  /**
+   * Warning: EIP-1191 checksum addresses are generally not backwards compatible with the
+   * wider Ethereum ecosystem, meaning it will break when validated against an application/tool
+   * that relies on EIP-55 checksum encoding (checksum without chainId).
+   *
+   * It is highly recommended to not use this feature unless you
+   * know what you are doing.
+   *
+   * See more: https://github.com/ethereum/EIPs/issues/1121
+   */
   chainId?: number | undefined,
 ): Address {
+  if (checksumAddressCache.has(`${address_}.${chainId}`))
+    return checksumAddressCache.get(`${address_}.${chainId}`)!
+
   const hexAddress = chainId
     ? `${chainId}${address_.toLowerCase()}`
     : address_.substring(2).toLowerCase()
@@ -35,15 +51,30 @@ export function checksumAddress(
     }
   }
 
-  return `0x${address.join('')}`
+  const result = `0x${address.join('')}` as const
+  checksumAddressCache.set(`${address_}.${chainId}`, result)
+  return result
 }
 
 export type GetAddressErrorType =
   | ChecksumAddressErrorType
   | IsAddressErrorType
   | ErrorType
 
-export function getAddress(address: string, chainId?: number): Address {
+export function getAddress(
+  address: string,
+  /**
+   * Warning: EIP-1191 checksum addresses are generally not backwards compatible with the
+   * wider Ethereum ecosystem, meaning it will break when validated against an application/tool
+   * that relies on EIP-55 checksum encoding (checksum without chainId).
+   *
+   * It is highly recommended to not use this feature unless you
+   * know what you are doing.
+   *
+   * See more: https://github.com/ethereum/EIPs/issues/1121
+   */
+  chainId?: number,
+): Address {
   if (!isAddress(address, { strict: false }))
     throw new InvalidAddressError({ address })
   return checksumAddress(address, chainId)