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Documentation Index

Fetch the complete documentation index at: https://voltaire.tevm.sh/llms.txt

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Try it Live

Run ABI examples in the interactive playground

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Overview

Abi.decodeData inspects calldata, matches the selector to a function in your ABI, and decodes the arguments. Use this when you have raw transaction calldata and want to recover the called function and parameters.

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Quick Start

import { Abi } from '@tevm/voltaire/Abi';
import { Hex } from '@tevm/voltaire/Hex';

const abi = Abi([
  {
    type: 'function',
    name: 'transfer',
    stateMutability: 'nonpayable',
    inputs: [
      { type: 'address', name: 'to' },
      { type: 'uint256', name: 'amount' }
    ],
    outputs: [{ type: 'bool' }]
  }
] as const);

const calldata = Hex.toBytes(
  '0xa9059cbb000000000000000000000000742d35cc6634c0532925a3b844bc9e7595f51e3e' +
  '00000000000000000000000000000000000000000000000000000000000003e8'
);

const decoded = abi.decodeData(calldata);
// { functionName: 'transfer', args: ['0x742d35...', 1000n] }

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Unknown Selectors

If the selector does not match any function in the ABI, Abi.decodeData throws AbiItemNotFoundError. 
import { Abi, AbiItemNotFoundError, AbiInvalidSelectorError } from '@tevm/voltaire/Abi';

try {
  abi.decodeData(calldata);
} catch (error) {
  if (error instanceof AbiInvalidSelectorError) {
    console.error('Calldata too short to contain a selector');
  }
  if (error instanceof AbiItemNotFoundError) {
    console.error('Unknown function selector');
  }
}

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Decode Parameters Without Selector

If you already know the function and only have parameters (no selector), decode with Abi.Function.decodeParams or Abi.decodeParameters: 
const transferFn = abi.getFunction('transfer');
const args = Abi.Function.decodeParams(transferFn, calldata);
// or
const params = Abi.decodeParameters(transferFn.inputs, calldata.slice(4));

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See Also