Skip to content
On this page

decodeFunctionData โ€‹

Decodes ABI encoded data (4 byte selector & arguments) into a function name and arguments.

The opposite of encodeFunctionData.

Install โ€‹

ts
import { decodeFunctionData } from 'viem'

Usage โ€‹

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

ts
import { decodeFunctionData } from 'viem'

const { functionName } = decodeFunctionData({
  abi: wagmiAbi,
  data: '0xc2985578'
})
// { functionName: 'totalSupply' }
ts
export const wagmiAbi = [
  ...
  {
    inputs: [],
    name: "totalSupply",
    outputs: [{ name: "", type: "uint256" }],
    stateMutability: "view",
    type: "function",
  },
  ...
] as const;
ts
import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

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

Extracting Arguments โ€‹

If your calldata includes argument(s) after the 4byte function signature, you can extract them with the args return value.

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

const { functionName, args } = decodeFunctionData({
  abi: wagmiAbi,
  data: '0x0423a1320000000000000000000000000000000000000000000000000000000000000001'
})
// { functionName: 'balanceOf', args: [1n] }
ts
export const wagmiAbi = [
  ...
  {
    inputs: [{ name: "owner", type: "address" }],
    name: "balanceOf",
    outputs: [{ name: "", type: "uint256" }],
    stateMutability: "view",
    type: "function",
  },
  ...
] as const;
ts
import { createPublicClient, http } from 'viem'
import { mainnet } from 'viem/chains'

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

Return Value โ€‹

ts
{
  functionName: string;
  args: unknown[] | undefined;
}

Decoded ABI function data.

functionName โ€‹

  • Type: string

The decoded function name.

args โ€‹

  • Type: unknown[] | undefined

The decoded function arguments.

Parameters โ€‹

abi โ€‹

The contract's ABI.

ts
const { functionName } = decodeFunctionData({
  abi: wagmiAbi, 
  data: '0xc2985578'
})

data โ€‹

The encoded calldata.

ts
const { functionName } = decodeFunctionData({
  abi: wagmiAbi,
  data: '0xc2985578' 
})

Released under the MIT License.