esbuild example API

Package: @tevm/example-esbuild · Source: apps/esbuild

This app is written in JavaScript with JSDoc types rather than TypeScript, which is why it also ships a hand-written addresses.d.ts.

src/ownerOf.js

publicClient

const publicClient: PublicClient

A viem public client pointed at Ethereum mainnet via rpcUrls.

import { publicClient } from './ownerOf.js'
 
const blockNumber = await publicClient.getBlockNumber()

ownerOf

function ownerOf(tokenId?: bigint): Promise<`0x${string}`>

Reads ownerOf(tokenId) on the mainnet deployment of ExampleContract. tokenId defaults to 1n.

The ABI, function name, and argument types all come from the Solidity import, so renaming the function in ExampleContract.sol breaks this call at build time.

Throws — if RPC_URL_MAINNET points at an unreachable endpoint, or if the token does not exist (ERC721 ownerOf reverts and viem throws a ContractFunctionExecutionError).

import { ownerOf } from './ownerOf.js'
 
console.log(await ownerOf())            // owner of token 1
console.log(await ownerOf(BigInt(420))) // owner of token 420

src/constants.js

rpcUrls

const rpcUrls: { 1: string }

RPC endpoints keyed by chain id. Validated with zod at module load rather than at first request, so a malformed RPC_URL_MAINNET fails immediately with a readable error instead of surfacing as a network failure deep inside a contract call. Falls back to mainnet.rpcUrls.default.http[0] when the variable is unset.

Throws — a ZodError if RPC_URL_MAINNET is set but is not a valid URL.

import { mainnet } from 'viem/chains'
import { rpcUrls } from './constants.js'
 
console.log(rpcUrls[mainnet.id])

src/addresses.js

addresses

const addresses: Record<'1' | '5' | '10' | '56' | '137' | '250' | '288' | '324' | '420' | '42161' | '80001' | '421613', `0x${string}`>

Deployment addresses of ExampleContract, keyed by chain id. src/addresses.d.ts types each value as a string literal so addresses[1] narrows to a viem Address without a cast.

import { addresses } from './addresses.js'
 
console.log(addresses[1]) // '0xFBA3912Ca04dd458c843e2EE08967fC04f3579c2'

src/index.js

Entry point bundled to dist/index.js. Calls ownerOf() and logs the result:

import { ownerOf } from './ownerOf.js'
 
ownerOf().then(console.log).catch(console.error)

build.js

Not an exported module — the esbuild driver. See the esbuild guide for the full configuration.