How to Set Up a Trust Line | XRPL Development in JavaScript Level 1

What is a Trust Line?

The trust line feature of XRPL (XRP Ledger) allows users to show their intention to accept specific currencies. This is used to handle assets other than XRP on XRPL. For example, if a user wants to accept another currency or a token from another issuer, they need to set a trust line for that currency or token.

The trust line feature allows users to hold and trade assets issued by other users or issuers in their accounts. For example, Alice can receive tokens issued by Charlie by setting a trust line for Charlie’s tokens.

One benefit is that it prevents unauthorized tokens from being sent to a user’s address, maintaining order among users.

Prerequisites

This guide proceeds with the following characters:

• Charlie (Token Issuer)
• Alice (Token Recipient)

Create the Script

The following is a script to set a trust line for Charlie’s tokens from Alice.

1. Create a new file named trust_set.js in your project directory.

2. Paste the following code into trust_set.js.

   const xrpl = require('xrpl');
   
   // Function to send a TrustSet transaction
   async function trustSet(recipientSecret) {
       // Connect to the Testnet server
       const client = new xrpl.Client('wss://s.altnet.rippletest.net:51233');
       await client.connect();
   
       try {
           // Wallet address of the token issuer (Charlie)
           const issuerWalletAddress = 'charlie_wallet_address_here';
   
           // Set the recipient's wallet
           const recipientWallet = xrpl.Wallet.fromSecret(recipientSecret);
   
           // Fixed information about the token
           const currencyCode = 'DOJ'; // Currency code
           const amount = '10000'; // Maximum receivable amount of tokens
   
           // Send the TrustSet transaction
           const response = await client.submitAndWait(
               {
                   TransactionType: 'TrustSet', // Set the trust line
                   Account: recipientWallet.address, // Alice's address
                   LimitAmount: {
                       issuer: issuerWalletAddress, // Issuer's address (Charlie)
                       currency: currencyCode, // DOJ
                       value: amount, // 10000
                   },
               },
               { wallet: recipientWallet } // Sign with Alice's wallet
           );
   
           // Output the result to the console
           console.log('Transaction result:', response);
       } catch (error) {
           // Error handling
           console.error('An error occurred:', error);
       }
   
       // Disconnect from the server
       client.disconnect();
   }
   
   // Execute the function
   const recipientSecret = 'alice_wallet_secret_here'; // Set Alice's secret key
   trustSet(recipientSecret);

   1. Enter Charlie’s testnet address in charlie_wallet_address_here.
   2. Enter Alice’s testnet secret key in alice_wallet_secret_here.

Run the Script

1. Run the following command in the command line to execute the script.

   node trust_set.js

   If successful, the console will display the following.

   Transaction result: {
       id: 14,
       result: {
           Account: 'rQr8KfkCQcpqvFwmRspDoaL36reZhcdaeA', // Alice's address
           Fee: '12',
           Flags: 0,
           LastLedgerSequence: 474997,
           LimitAmount: {
               currency: 'DOJ', // Currency code
               issuer: 'rh8xETfGs1Ktizj9EXZb5QpW4aqk8bWUSU', // Token issuer's address (Charlie)
               value: '10000' // Maximum amount of DOJ tokens Alice can receive
           },
           Sequence: 474064,
           SigningPubKey: 'ED2924DBD08E093DD7FC9C35B8DCEBD74CA4C8349D68D7BF566AD6C2533B8BB865',
           TransactionType: 'TrustSet',
           TxnSignature: '8245C9412BA9E247D962B2D9B9B6B74A90D3757FDA66422527611971004F94D803607A3CC5357BA83B0FA0B7D010B10F3D0F5188EE8D4F1D72181BFA4D052B0B',
           ctid: 'C0073F6300000001',
           date: 768402681,
           hash: 'A20A377A4E9D8CAAA62E5AEE7CDFB9FBC690171B1D13485AC40A6313996A98C8', // Hash value
           inLedger: 474979,
           ledger_index: 474979, // Ledger index number
           meta: {
               AffectedNodes: [Array],
               TransactionIndex: 0,
               TransactionResult: 'tesSUCCESS' // Success
           },
           validated: true // Validated transaction
       },
       type: 'response'
   }

   Now Alice can receive the DOJ tokens issued by Charlie.