How to pay rent fee when creating solana wallet in nodejs

Question

hello I create solana wallet with the following code on my nodejs server.

const SolanaWeb3 = require("@solana/web3.js"); 
SolanaWeb3.Keypair.generate();

I don't think this is an active wallet. Because I haven't paid the rent fee for this account.

**So I want to know when is the moment when this inactive account pays the rent fee. (I want to know if it is activated when a transaction in which sol is deposited into this account occurs, or whether this account should generate a transaction that sends solana to another place.)

And I want to know if there is a javascript function that gives rent fee when account is created.**

thank you for your reply.

Answer 1

To your second question

And I want to know if there is a javascript function that gives rent fee when account is created

Yes there is. Assuming you just want a system account that holds SOL versus an account that has data:

  // amount of space to reserve for the account. system accounts are 0 space
  const space = 0;

  // Get the rent, in lamports, for exemption
  const rentExemptionAmount =
    await connection.getMinimumBalanceForRentExemption(space);

To your first question

If you already have a funded account (fromKeyPair), you can use that accounts public key to fund the new account you want to create:

  const newAccountKeypair = SolanaWeb3.Keypair.generate();

  const createAccountParams = {
    fromPubkey: fromKeyPair.publicKey,
    newAccountPubkey: newAccountKeypair.publicKey,
    lamports: rentExemptionAmount,
    space,
    programId: SolanaWeb3.SystemProgram.programId,
  };


  const createAccountTransaction = new SolanaWeb3.Transaction().add(
    SolanaWeb3.SystemProgram.createAccount(createAccountParams)
  );

  await SolanaWeb3.sendAndConfirmTransaction(connection, createAccountTransaction, [
    fromKeyPair,
    newAccountKeypair,
  ]);