How to Close a Payment Channel | XRPL Development in JavaScript - Level 4

In this chapter, we will explain how to close a payment channel.

Closing a payment channel allows you to reclaim unused funds and finalize the channel’s remaining balance.

Preparation

Create a new file named closePaymentChannel.js in your project directory.

Paste the following code into closePaymentChannel.js.

import { PaymentChannelClaimFlags } from 'xrpl';
import { client, bobWallet } from './config.js';

const closePaymentChannel = async (channelId) => {
    try {
        // Create a PaymentChannelClaim transaction
        const tx = {
            TransactionType: 'PaymentChannelClaim',
            Account: bobWallet.address, // Sender (Bob)'s account address
            Channel: channelId, // Channel ID
            Flags: PaymentChannelClaimFlags.tfClose, // Close flag: 131072
        };

        console.log('Submitting a PaymentChannelClaim transaction to close the channel...');

        // Submit the transaction
        const closeChannelResponse = await client.submitAndWait(tx, {
            wallet: bobWallet,
        });

        console.log(
            'PaymentChannelClaim (close) transaction response:',
            closeChannelResponse
        );
    } catch (error) {
        console.error('Error closing Payment Channel:', error);
    }
};

const main = async () => {
    try {
        await client.connect();
        const channelId = 'CHANNEL_ID_HERE'; // Enter the previously created channel ID
        await closePaymentChannel(channelId);
    } catch (error) {
        console.error('Error connecting to XRPL:', error);
    } finally {
        await client.disconnect();
    }
};

main();

Running the Script

Execute the script by running the following command in your command line:
Terminal window
```
node closePaymentChannel.js
```

If successful, the console will display the following:

Submitting a PaymentChannelClaim transaction to close the channel...
PaymentChannelClaim (close) transaction response: {
    id: 10,
    result: {
        Account: 'rDW8W3rzDFUyU4pw5Ei8QL1J9nQ947h68f',
        Channel: '25C67138FB51F65A7015632C07E00AD0AE1C8A21F0282FD0401BAEDFDFD3423E',
        Fee: '12',
        Flags: 131072,
        LastLedgerSequence: 1745129,
        Sequence: 1742743,
        SigningPubKey: 'ED9F9B58A0A209A1D0F90832FE83F3ED49C0091259E3F67A2FCAA3D3EAAF718FFE',
        TransactionType: 'PaymentChannelClaim',
        TxnSignature: '192E1D8F6A8887446A27AA54C41C226A46B3C43A4D780654696A74D9454A6E3B52EBB5D57C420F6CF597F68D6B16EE57F8DCE7F1A5653216632A9B0CA19D5601',
        ctid: 'C01AA0D700000001',
        date: 772457030,
        hash: '8BF8ACC66D4B61A106CFC5A916EA8DAE621C5362D9DA6F7C08E720FEDE5733B6',
        inLedger: 1745111,
        ledger_index: 1745111,
        meta: {
            AffectedNodes: [Array],
            TransactionIndex: 0,
            TransactionResult: 'tesSUCCESS'
        },
        validated: true
    },
    type: 'response'
}

About the Channel Closing Process

Although we have set the close flag from Bob’s side, the channel will still exist for now.

Let’s review the createPaymentChannel.js file.

const tx = {
    TransactionType: 'PaymentChannelCreate', // Transaction type: PaymentChannelCreate
    Account: bobWallet.address, // Sender (Bob)'s account address
    Amount: xrpToDrops('10'), // Amount of XRP to deposit into the channel (10 XRP in this case)
    Destination: aliceWallet.address, // Receiver (Alice)'s account address
    SettleDelay: 86400, // Grace period before the channel can be closed if there are unclaimed XRP (1 day in this case)
    PublicKey: bobWallet.publicKey, // Sender (Bob)'s public key
    CancelAfter: unixTimeToRippleTime(Math.floor(Date.now() / 1000) + 86400 * 30), // Seconds until the channel is canceled (1 month in this case)
};

Here, SettleDelay was specified as 1 day.

When the sender closes the channel, the SettleDelay period must pass before the channel is officially closed. This means that the channel will be closed 1 day after the close flag is set.

If possible, run node checkChannelBalance.js to confirm that the channel still exists.

Channel ID: 25C67138FB51F65A7015632C07E00AD0AE1C8A21F0282FD0401BAEDFDFD3423E
Balance: 1000000 drops
Amount: 15000000 drops

Reopening the Channel

You can reopen the channel by changing the Flags value. Only the source address of the payment channel can use this flag.

const tx = {
    TransactionType: 'PaymentChannelClaim',
    Account: bobWallet.address, // 送金人（ボブ）のアカウントアドレス
    Channel: channelId, // チャネルID
    Flags: PaymentChannelClaimFlags.tfRenew, // 再開フラグ: 65536
};

Closing the Channel from the Receiver’s Side

When the receiver (Alice) closes the channel, the channel is forcibly terminated.

Running the Script

Modify the closePaymentChannel.js code as follows:

const closePaymentChannel = async (channelId) => {
    try {
        // Create a PaymentChannelClaim transaction
            const tx = {
            TransactionType: 'PaymentChannelClaim',
            // Account: bobWallet.address, // Sender (Bob)'s account address
            Account: aliceWallet.address, // Receiver (Alice)'s account address
            Channel: channelId, // Channel ID
            Flags: PaymentChannelClaimFlags.tfClose, // Close flag: 131072
            validated: true,
        };

        console.log(
            'Submitting a PaymentChannelClaim transaction to close the channel...'
        );

        const closeChannelResponse = await client.submitAndWait(tx, {
            // wallet: bobWallet,
            wallet: aliceWallet,
        });

        console.log(
            'PaymentChannelClaim (close) transaction response:',
            closeChannelResponse
        );
    } catch (error) {
        console.error('Error closing Payment Channel:', error);
    }
};

Run the script by executing the following command in your command line:
Terminal window
```
node closePaymentChannel.js
```

If successful, the console will display the following:

Submitting a PaymentChannelClaim transaction to close the channel...
PaymentChannelClaim (close) transaction response: {
    id: 10,
    result: {
        Account: 'rDW8W3rzDFUyU4pw5Ei8QL1J9nQ947h68f',
        Channel: '25C67138FB51F65A7015632C07E00AD0AE1C8A21F0282FD0401BAEDFDFD3423E',
        Fee: '12',
        Flags: 131072,
        LastLedgerSequence: 1745129,
        Sequence: 1742743,
        SigningPubKey: 'ED9F9B58A0A209A1D0F90832FE83F3ED49C0091259E3F67A2FCAA3D3EAAF718FFE',
        TransactionType: 'PaymentChannelClaim',
        TxnSignature: '192E1D8F6A8887446A27AA54C41C226A46B3C43A4D780654696A74D9454A6E3B52EBB5D57C420F6CF597F68D6B16EE57F8DCE7F1A5653216632A9B0CA19D5601',
        ctid: 'C01AA0D700000001',
        date: 772457030,
        hash: '8BF8ACC66D4B61A106CFC5A916EA8DAE621C5362D9DA6F7C08E720FEDE5733B6',
        inLedger: 1745111,
        ledger_index: 1745111,
        meta: {
            AffectedNodes: [Array],
            TransactionIndex: 0,
            TransactionResult: 'tesSUCCESS'
        },
        validated: true
    },
    type: 'response'
}

Run the checkChannelBalance.js script again to check the channel’s status.
```
node checkChannelBalance.js
```
If the following result is displayed, the channel has been fully closed.
Terminal window
```
Channel with ID 25C67138FB51F65A7015632C07E00AD0AE1C8A21F0282FD0401BAEDFDFD3423E not found.
```
Let’s check the balances of Alice and Bob on a test network explorer like Bithomp.

Assuming the steps were followed correctly, the deposited XRP should be returned to Bob, resulting in the following balances:
- Alice: approximately 100 XRP
- Bob: approximately 89 XRP

Summary

In this chapter, we explained how to close a payment channel.

By using the PaymentChannelClaim transaction to close the channel, you can reclaim unused funds and finalize the channel’s remaining balance.

Completing this guide should give you a solid understanding of the basic transaction flow using payment channels.

Payment channels are among the more complex features of XRPL, so it can be challenging to grasp the concept from documentation alone.

We hope this knowledge proves useful in your future development and projects.

*The next chapter is under construction.