encodeFunctionData ​

Encodes the function name and parameters into an ABI encoded value (4 byte selector & arguments).

Install ​

import { encodeFunctionData } from 'viem'

Usage ​

Below is a very basic example of how to encode a function to calldata.

import { encodeFunctionData } from 'viem'

const data = encodeFunctionData({
  abi: wagmiAbi,
  functionName: 'totalSupply'
})

export const wagmiAbi = [
  ...
  {
    inputs: [],
    name: "totalSupply",
    outputs: [{ name: "", type: "uint256" }],
    stateMutability: "view",
    type: "function",
  },
  ...
] as const;

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})

Passing Arguments ​

If your function requires argument(s), you can pass them through with the args attribute.

TypeScript types for args will be inferred from the function name & ABI, to guard you from inserting the wrong values.

For example, the balanceOf function name below requires an address argument, and it is typed as ["0x${string}"].

import { encodeFunctionData } from 'viem'
import { publicClient } from './client'
import { wagmiAbi } from './abi'

const data = encodeFunctionData({
  abi: wagmiAbi,
  functionName: 'balanceOf',
  args: ['0xa5cc3c03994DB5b0d9A5eEdD10CabaB0813678AC']
})

export const wagmiAbi = [
  ...
  {
    inputs: [{ name: "owner", type: "address" }],
    name: "balanceOf",
    outputs: [{ name: "", type: "uint256" }],
    stateMutability: "view",
    type: "function",
  },
  ...
] as const;

import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

export const publicClient = createPublicClient({
  chain: mainnet,
  transport: http()
})

Without functionName ​

If your abi contains only one ABI item, you can omit the functionName (it becomes optional):

import { encodeFunctionData } from 'viem'

const abiItem = {
  inputs: [{ name: 'owner', type: 'address' }],
  name: 'balanceOf',
  outputs: [{ name: '', type: 'uint256' }],
  stateMutability: 'view',
  type: 'function',
}

const data = encodeFunctionData({
  abi: [abiItem],
  functionName: 'balanceOf', 
  args: ['0xa5cc3c03994DB5b0d9A5eEdD10CabaB0813678AC']
})

Return Value ​

Hex

ABI encoded data (4byte function selector & arguments).

Parameters ​

abi ​

• Type: Abi

The contract's ABI.

const data = encodeFunctionData({
  abi: wagmiAbi, 
  functionName: 'totalSupply',
})

functionName ​

• Type: string

The function to encode from the ABI.

const data = encodeFunctionData({
  abi: wagmiAbi,
  functionName: 'totalSupply', 
})

args (optional) ​

• Type: Inferred from ABI.

Arguments to pass to function call.

const data = encodeFunctionData({
  abi: wagmiAbi,
  functionName: 'balanceOf',
  args: ['0xa5cc3c03994DB5b0d9A5eEdD10CabaB0813678AC'] 
})