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Portal provides the function portal.simulateTransaction, which gives you insights into what will happen upon executing the transaction. Here’s how it works: 
const handleSimulateTransaction = async () => {
  // First, construct a transaction.
  const transaction = {
    to: '0xRecipientAddressHere', // {string} The recipient address.
    value: '0x10DE4A2A',  // {?string} The value to be sent in Wei.
    data: undefined,  // {?string} Data for the transaction (for contract interactions).
    maxFeePerGas: undefined, // {?string} Maximum fee per gas.
    maxPriorityFeePerGas: undefined, // {?string} Maximum priority fee per gas.
    gas: undefined, // {?string} The gas limit.
    gasPrice: undefined // {?string} Gas price in Wei.
  };

  // Next, simulate the transaction.
  const chainId = 'eip155:1'
  const simulatedResult = await portal.simulateTransaction(chainId, transaction);

  // Finally, you can handle or display the simulation results as needed.
  if (simulatedResult.error) {
    console.error("Transaction Error:", simulatedResult.error.message);
  } else if (simulatedResult.requestError) {
    console.error("Request Error:", simulatedResult.requestError.message);
  } else {
    console.log("Simulated Transaction Results:", simulatedResult.changes);
  }
}
This function will return a JSON object that breaks down the transaction simulation:
  • changes: An array detailing all the potential transaction outcomes. Each change has the following structure:
    • amount: The amount being transferred.
    • assetType: The type of asset being dealt with (NATIVE or ERC20 or ERC721 or ERC1155 or SPECIAL_NFT).
    • changeType: The type of change (APPROVE or TRANSFER).
    • contractAddress: Address of the contract being interacted with (null for native transactions).
    • decimals: Decimals used in the asset.
    • from: The sender address.
    • name: The name of the asset.
    • rawAmount: The unformatted amount being transferred.
    • symbol: The asset’s symbol.
    • to: The receiver’s address.
    • tokenId: An identifier for tokens (null for assets that are not tokens).
  • gasUsed: The gas used by the transaction.
  • error: An object that contains the error message if the transaction would fail upon execution.
  • requestError: An object that contains the error message if there was an issue with the request, such as a malformed transaction argument being provided.
By incorporating transaction simulations, you can provide your users with a preview of the transaction outcomes and preemptively detect and handle errors, ensuring a smoother user experience. And now you are simulating transactions with Portal! 🙌 🚀 Next, we’ll explore how to back up the wallet for recovery if the user loses device access.
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