We are now going to learn how to manage accounts and send transactions:

1. To view the list of accounts available in the connected node, use the following command:

// v0.2x.x
web3.eth.accounts;

// v1.x.x
web3.eth.getAccounts().then(console.log);

2. To create an account using the web3 object, run the following command. Starting from 1.x.x, web3.js includes added support for account management:

// For v1.x.x
web3.eth.accounts.create();
web3.eth.accounts.create("<random entropy>");

The create function accepts an entropy as input for randomness. If not specified, it will generate a random hex of 32 bytes by using web3.utils.randomHex(32) and will use it as the entropy input. This method will return the new address, private key, and methods associated with it:

{ 
    address: '0x824e470cCac64CC5fa4Abe953e64FA360EA11366',
    privateKey: '0x782174a3e404424af...499baffd30e6105f',
    signTransaction: [Function: signTransaction],
    sign: [Function: sign],
    encrypt: [Function: encrypt]
}

3. If you already have a private key, import it using the privateKeyToAccount function:

// For v1.x.x
web3.eth.accounts.privateKeyToAccount("<privateKey>");

4. Unlock your account with the passphrase before sending a transaction. Authentication works differently for a raw transaction, which we will focus on in the Sending a raw transaction recipe later in this chapter. You can try unlocking your account with the following scripts:

// For v0.2x.x
web3.personal.unlockAccount("<address>", "<password>", <duration>);

// For v1.x.x
web3.eth.personal.unlockAccount("<address>", "<password>", <duration>)
    .then(console.log);

5. To send a transaction, use the sendTransaction method with the required parameters:

web3.eth.sendTransaction(transaction_object [, callback])

You can use the following parameters to create the transaction object:

• from: Address of the sending account. The default is web3.eth.defaultAccount.
• to (optional): Address of the destination account. Leave it blank if you are creating a contract.
• value (optional): The value transferred through the transaction in Wei.
• gas (optional): The maximum amount of gas to use for the transaction.
• gasPrice (optional): The price of gas for this transaction in Wei. The default is web3.eth.gasPrice.
• data (optional): Either the data of the function call or the contract initialization code.
• nonce (optional): Nonce value for the transaction. You can use this to overwrite a transaction by providing the same nonce value as the older transaction.

Here is an example that uses these parameters:

web3.eth.sendTransaction({
    from: "0xce5C2D181f6DD99091351f6E6056c333A969AEC9",
    to: "",
    gas:21000,
    gasPrice: 20000000000, // 20 Gwei
    value: 200000
}, function(error, transactionHash) {
    if(!error) 
        console.log(transactionHash);
})

6. Starting from web3.js 1.0.0, the sendTransaction method returns a promise combined with an event emitter. This can help perform different tasks based on various stages of a transaction. Consider the following example:

web3.eth.sendTransaction({
    from: "0xce5C2D181f6DD99091351f6E6056c333A969AEC9",
    to: 0x71495cd51c5356B1f0769dB5027DC0588010dC14,
    value: '10000000000000000'
})
.on('transactionHash', function(hash){
    console.log(hash);
})
.on('receipt', function(receipt){
    console.log(receipt);
})
.on('confirmation', function(confirmationNumber, receipt){ 
    console.log(confirmationNumber);
})
.on('error', console.error);

Let's look into each event in detail:

• transactionHash: It is fired immediately after a transaction hash is available.
• receipt: It is fired when the transaction receipt is generated.
• confirmation: It is fired for every confirmation up to the 12^th confirmation, starting from 0th confirmation.
• error: It is fired if an error occurs during the transaction. For out of gas errors, the second parameter is the transaction receipt.