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Sample dApp RNS Integration

This guide walks you through building a React dApp that integrates with the Rootstock Name Service (RNS) using ethers.js. You'll create a functional application that allows users to resolve domain names to addresses, check domain availability, perform reverse lookups, and more etc.

By the end of this guide, you'll have a dApp that demonstrates core RNS operations and serves as a foundation for building more complex blockchain applications on Rootstock.

Prerequisites

Before starting, ensure you have the following:

Node.js and npm installed
A wallet preferably MetaMask configured for Rootstock Mainnet or Testnet
Basic understanding of Solidity and Web3.js or ethers.js
Rootstock Testnet Faucet

メモ

All the code snippets shown in this guide will be added inside your App.js file.

1. Project Setup

Before you begin, ensure you have a React app set up. If not, create one with:

npx create-react-app rns-dapp
cd rns-dapp

Then install the required dependencies:

npm install ethers @ethersproject/providers @ethersproject/contracts @ethersproject/constants @ethersproject/hash react-dom react-scripts @rsksmart/rns

2. Change Index.js to React Dom

Go to index.js and change it to the following code:

import App from './App';
import './index.css';

ReactDOM.render(
  <App />,
  document.getElementById('root')
);
``

### 3. Import the Required Modules

Open your `App.js` file and import the following modules:

```js
import React, { useState, useCallback, useMemo } from "react";
import { JsonRpcProvider } from "@ethersproject/providers";
import { Contract } from "@ethersproject/contracts";
import { AddressZero } from "@ethersproject/constants";
import { namehash } from "@ethersproject/hash";

4. Initialize RNS

Next, set up RNS using the RNS Registry Contract Address and the RSK Testnet RPC URL.

Add the following code inside App.js:

// Rootstock Testnet RPC
const ROOTSTOCK_RPC_NODE = "https://public-node.testnet.rsk.co";

// RNS registry (testnet)
const RNS_REGISTRY_ADDRESS = "0x7d284aaac6e925aad802a53c0c69efe3764597b8";

// Bitcoin chain ID for multichain resolver
const BITCOIN_CHAIN_ID = 0;

// ABIs
const RNS_REGISTRY_ABI = [
  "function resolver(bytes32 node) view returns (address)",
  "function owner(bytes32 node) view returns (address)",
];

const RNS_ADDR_RESOLVER_ABI = [
  "function addr(bytes32 node) view returns (address)",
  "function addr(bytes32 node, uint coinType) view returns (bytes)",
];

const RNS_NAME_RESOLVER_ABI = [
  "function name(bytes32 node) view returns (string)",
];

const provider = new JsonRpcProvider(ROOTSTOCK_RPC_NODE);

const registry = new Contract(
  RNS_REGISTRY_ADDRESS,
  RNS_REGISTRY_ABI,
  provider
);

What this does:

Connects to the Rootstock Testnet
Initializes the RNS Registry contract
Sets up the provider for contract interactions

5. Utility Functions

Add a utility function to strip the hex prefix from addresses:

const stripHexPrefix = (hex: string): string => hex.slice(2);

6. Style for the UI

Add the following style for the UI:

const styles = {
 container: {
   minHeight: "100vh",
   backgroundColor: "#f5f6fa",
   display: "flex",
   justifyContent: "center",
   alignItems: "center",
   padding: "20px",
   fontFamily: "Arial, sans-serif",
 },
 card: {
   backgroundColor: "#fff",
   padding: "25px",
   borderRadius: "10px",
   maxWidth: "520px",
   width: "100%",
   boxShadow: "0 2px 6px rgba(0,0,0,0.1)",
 },
 heading: {
   textAlign: "center",
   marginBottom: "20px",
   fontSize: "22px",
 },
 input: {
   padding: "10px",
   width: "100%",
   borderRadius: "6px",
   border: "1px solid #ccc",
   marginBottom: "10px",
   boxSizing: "border-box",
 },
 buttonGroup: {
   display: "flex",
   gap: "10px",
   marginBottom: "10px",
 },
 button: {
   flex: 1,
   padding: "10px",
   backgroundColor: "#388e3c",
   color: "#fff",
   border: "none",
   borderRadius: "6px",
   cursor: "pointer",
 },
 buttonAlt: {
   flex: 1,
   padding: "10px",

   backgroundColor: "#1976d2",
   color: "#fff",
   border: "none",
   borderRadius: "6px",
 },
 buttonWide: {
   width: "100%",
   padding: "10px",
   backgroundColor: "#5e35b1",
   color: "#fff",
   border: "none",
   borderRadius: "6px",
   margin: "10px",
   marginBottom: "5px",
 },
 ownerBox: {
   padding: "10px",
   backgroundColor: "#e8f5e9",
   borderRadius: "6px",
   border: "1px solid #c8e6c9",
   marginTop: "10px",
 },
 divider: {
   margin: "20px 0",
   borderTop: "1px solid #ddd",
 },
 resultBox: {
   marginTop: "10px",
   padding: "10px",
   backgroundColor: "#f9f9f9",
   border: "1px solid #ddd",
   borderRadius: "6px",
 },
};

7. Core RNS Functions

Add the core functions that handle different RNS operations.

a. Resolve a Rootstock Address

Looks up the RSK address linked to a given RNS domain:

const resolveRnsName = async (name) => {
  try {
    const nameHash = namehash(name);
    const resolverAddress = await registry.resolver(nameHash);

    if (resolverAddress === AddressZero) {
      return null;
    }

    const addrResolverContract = new Contract(
      resolverAddress,
      RNS_ADDR_RESOLVER_ABI,
      provider
    );

    // Use the functions property to call overloaded functions
    const [address] = await addrResolverContract.functions["addr(bytes32)"](
      nameHash
    );

    if (!address || address === AddressZero) {
      return null;
    }

    return address.toLowerCase();
  } catch (e) {
    console.error("resolveRnsName error", e);
    return null;
  }
};

Important Note on Overloaded Functions

When working with overloaded contract functions in ethers.js, you must use the functions property with the full function signature (e.g., functions["addr(bytes32)"]). This is necessary because the RNS resolver contract has multiple addr functions with different parameters.

b. Resolve a Bitcoin Address

Fetches the Bitcoin address if the domain has one:

const resolveBitcoinAddress = async (name) => {
  try {
    const hash = namehash(name);
    const resolver = await registry.resolver(hash);

    if (resolver === AddressZero) return null;

    const resolverContract = new Contract(
      resolver,
      RNS_ADDR_RESOLVER_ABI,
      provider
    );

    const [btcBytes] = await resolverContract.functions[
      "addr(bytes32,uint256)"
    ](hash, BITCOIN_CHAIN_ID);

    if (!btcBytes || btcBytes === "0x") return null;

    return btcBytes;
  } catch (e) {
    console.error("resolveBitcoinAddress error", e);
    return null;
  }
};

c. Reverse Lookup (Address to Name)

Looks up the RNS name associated with an address:

const lookupAddress = async (address) => {
  try {
    const reverseHash = namehash(`${stripHexPrefix(address)}.addr.reverse`);

    const resolver = await registry.resolver(reverseHash);

    if (resolver === AddressZero) return null;

    const resolverContract = new Contract(
      resolver,
      RNS_NAME_RESOLVER_ABI,
      provider
    );

    const name = await resolverContract.name(reverseHash);
    return name || null;
  } catch (e) {
    console.error("lookupAddress error", e);
    return null;
  }
};

d. Get Domain Owner

Retrieves the owner address of a domain:

const getDomainOwner = async (domain) => {
 try {
   const hash = namehash(domain);
   const owner = await registry.owner(hash);
   if (!owner || owner === AddressZero) return null;
   return owner.toLowerCase();
 } catch (e) {
   console.error("owner error", e);
   return null;
 }
}
;

e. Check Domain Availability

Checks if a domain is available for registration:

const checkDomainAvailability = async (domain) => {
  try {
    const hash = namehash(domain);
    const owner = await registry.owner(hash);
    return owner === AddressZero;
  } catch (e) {
    console.error("availability error", e);
    return false;
  }
};

f. Check Subdomain Availability

Checks if a subdomain is available:

const checkSubdomainAvailability = async (
 domain,
 subdomain
)=> {
 return checkDomainAvailability(`${subdomain}.${domain}`);
};

6. Custom RNS Hook

Create a custom hook to encapsulate all RNS functionality:

const useRns = () => {
  const getAddressByRns = useCallback(async (name) => {
    return await resolveRnsName(name);
  }, []);

  const getBitcoinAddressByRns = useCallback(async (name) => {
    return await resolveBitcoinAddress(name);
  }, []);

  const getRnsName = useCallback(async (address) => {
    return await lookupAddress(address);
  }, []);

  const getOwner = useCallback(async (domain) => {
    return await getDomainOwner(domain);
  }, []);

  const checkAvailability = useCallback(async (domain) => {
    return await checkDomainAvailability(domain);
  }, []);

  const checkSubdomain = useCallback(
    async (domain: string, subdomain: string) => {
      return await checkSubdomainAvailability(domain, subdomain);
    },
    []
  );

  return useMemo(
    () => ({
      getAddressByRns,
      getBitcoinAddressByRns,
      getRnsName,
      getOwner,
      checkAvailability,
      checkSubdomain,
    }),
    [
      getAddressByRns,
      getBitcoinAddressByRns,
      getRnsName,
      getOwner,
      checkAvailability,
      checkSubdomain,
    ]
  );
};

8. Main Component

Create the main component with UI and event handlers inside the same App.js:

export default function App() {
  const {
    getAddressByRns,
    getBitcoinAddressByRns,
    getRnsName,
    getOwner,
    checkAvailability,
    checkSubdomain,
  } = useRns();

  const [domain, setDomain] = useState("");
  const [subdomain, setSubdomain] = useState("");
  const [address, setAddress] = useState("");
  const [result, setResult] = useState("");
  const [owner, setOwner] = useState("");
  const [loading, setLoading] = useState(false);

  const wrap = async (fn) => {
    setLoading(true);
    setResult("");
    setOwner("");
    try {
      await fn();
    } finally {
      setLoading(false);
    }
  };

  return (
    <div style={styles.container}>
      <div style={styles.card}>
        <h1 style={styles.heading}>Rootstock Name Service Lookup</h1>

        <input
          style={styles.input}
          value={domain}
          onChange={(e) => setDomain(e.target.value)}
          placeholder="Enter domain like testing.rsk"
        />

        <div style={styles.buttonGroup}>
          <button
            style={styles.button}
            disabled={loading}
            onClick={() =>
              wrap(async () => {
                const addr = await getAddressByRns(domain);
                setResult(addr || "No RSK address found");
              })
            }
          >
            Resolve RSK
          </button>

          <button
            style={styles.buttonAlt}
            disabled={loading}
            onClick={() =>
              wrap(async () => {
                const btc = await getBitcoinAddressByRns(domain);
                setResult(btc || "No Bitcoin address found");
              })
            }
          >
            Resolve BTC
          </button>
        </div>

        <button
          style={styles.buttonWide}
          disabled={loading}
          onClick={() =>
            wrap(async () => {
              const available = await checkAvailability(domain);
              setResult(
                available ? "✅ Domain is available" : "❌ Domain is taken"
              );
            })
          }
        >
          Check Availability
        </button>

        <div style={{ display: "flex", gap: "8px" }}>
          <input
            style={{ ...styles.input, flex: 1 }}
            value={subdomain}
            onChange={(e) => setSubdomain(e.target.value)}
            placeholder="Enter subdomain"
          />
          <button
            style={styles.buttonAlt}
            disabled={loading}
            onClick={() =>
              wrap(async () => {
                const available = await checkSubdomain(domain, subdomain);
                setResult(
                  available
                    ? "✅ Subdomain is available"
                    : "❌ Subdomain is taken"
                );
              })
            }
          >
            Check Subdomain
          </button>
        </div>

        <button
          style={styles.buttonWide}
          disabled={loading}
          onClick={() =>
            wrap(async () => {
              const ownerAddr = await getOwner(domain);
              if (ownerAddr) {
                setOwner(ownerAddr);
                setResult("Owner found");
              } else {
                setResult("No owner found");
              }
            })
          }
        >
          Get Owner
        </button>

        {owner && (
          <div style={styles.ownerBox}>
            <strong>Owner:</strong> {owner}
          </div>
        )}

        <hr style={styles.divider} />

        <input
          style={styles.input}
          value={address}
          onChange={(e) => setAddress(e.target.value)}
          placeholder="Reverse lookup (address)"
        />

        <button
          style={styles.buttonWide}
          disabled={loading}
          onClick={() =>
            wrap(async () => {
              const name = await getRnsName(address);
              setResult(name || "No reverse entry found");
            })
          }
        >
          Reverse Lookup
        </button>

        <div style={styles.resultBox}>{loading ? "Loading..." : result}</div>
      </div>
    </div>
  );
}

Full App.js code

import React, { useState, useCallback, useMemo } from "react";
import { JsonRpcProvider } from "@ethersproject/providers";
import { Contract } from "@ethersproject/contracts";
import { AddressZero } from "@ethersproject/constants";
import { namehash } from "@ethersproject/hash";

const ROOTSTOCK_RPC_NODE = "https://public-node.testnet.rsk.co";

// RNS registry (testnet)
const RNS_REGISTRY_ADDRESS = "0x7d284aaac6e925aad802a53c0c69efe3764597b8";

// Bitcoin chain ID for multichain resolver
const BITCOIN_CHAIN_ID = 0;

// ABIs
const RNS_REGISTRY_ABI = [
"function resolver(bytes32 node) view returns (address)",
"function owner(bytes32 node) view returns (address)",
];

const RNS_ADDR_RESOLVER_ABI = [
"function addr(bytes32 node) view returns (address)",
"function addr(bytes32 node, uint coinType) view returns (bytes)",
];

const RNS_NAME_RESOLVER_ABI = [
"function name(bytes32 node) view returns (string)",
];

const provider = new JsonRpcProvider(ROOTSTOCK_RPC_NODE);

const registry = new Contract(RNS_REGISTRY_ADDRESS, RNS_REGISTRY_ABI, provider);

const stripHexPrefix = (hex) => hex.slice(2);
const styles = {
container: {
minHeight: "100vh",
backgroundColor: "#f5f6fa",
display: "flex",
justifyContent: "center",
alignItems: "center",
padding: "20px",
fontFamily: "Arial, sans-serif",
},
card: {
backgroundColor: "#fff",
padding: "25px",
borderRadius: "10px",
maxWidth: "520px",
width: "100%",
boxShadow: "0 2px 6px rgba(0,0,0,0.1)",
},
heading: {
textAlign: "center",
marginBottom: "20px",
fontSize: "22px",
},
input: {
padding: "10px",
width: "100%",
borderRadius: "6px",
border: "1px solid #ccc",
marginBottom: "10px",
boxSizing: "border-box",
},
buttonGroup: {
display: "flex",
gap: "10px",
marginBottom: "10px",
},
button: {
flex: 1,
padding: "10px",
backgroundColor: "#388e3c",
color: "#fff",
border: "none",
borderRadius: "6px",
cursor: "pointer",
},
buttonAlt: {
flex: 1,
padding: "10px",

backgroundColor: "#1976d2",
color: "#fff",
border: "none",
borderRadius: "6px",
},
buttonWide: {
width: "100%",
padding: "10px",
backgroundColor: "#5e35b1",
color: "#fff",
border: "none",
borderRadius: "6px",
margin: "10px",
marginBottom: "5px",
},
ownerBox: {
padding: "10px",
backgroundColor: "#e8f5e9",
borderRadius: "6px",
border: "1px solid #c8e6c9",
marginTop: "10px",
},
divider: {
margin: "20px 0",
borderTop: "1px solid #ddd",
},
resultBox: {
marginTop: "10px",
padding: "10px",
backgroundColor: "#f9f9f9",
border: "1px solid #ddd",
borderRadius: "6px",
},
};

// Resolve RSK address
const resolveRnsName = async (name) => {
try {
const nameHash = namehash(name);
const resolverAddress = await registry.resolver(nameHash);

if (resolverAddress === AddressZero) {
  return null;
}

const addrResolverContract = new Contract(
  resolverAddress,
  RNS_ADDR_RESOLVER_ABI,
  provider
);

// Use the functions property to call overloaded functions
const [address] = await addrResolverContract.functions["addr(bytes32)"](
  nameHash
);

if (!address || address === AddressZero) {
  return null;
}

return address.toLowerCase();
} catch (e) {
console.error("resolveRnsName error", e);
return null;
}
};

// Resolve BTC address
const resolveBitcoinAddress = async (name) => {
try {
const hash = namehash(name);
const resolver = await registry.resolver(hash);

if (resolver === AddressZero) return null;

const resolverContract = new Contract(
  resolver,
  RNS_ADDR_RESOLVER_ABI,
  provider
);

const [btcBytes] = await resolverContract.functions[
  "addr(bytes32,uint256)"
](hash, BITCOIN_CHAIN_ID);

if (!btcBytes || btcBytes === "0x") return null;

return btcBytes;
} catch (e) {
console.error("resolveBitcoinAddress error", e);
return null;
}
};

// Reverse lookup (address to name)
const lookupAddress = async (address) => {
try {
const reverseHash = namehash(`${stripHexPrefix(address)}.addr.reverse`);

const resolver = await registry.resolver(reverseHash);

if (resolver === AddressZero) return null;

const resolverContract = new Contract(
  resolver,
  RNS_NAME_RESOLVER_ABI,
  provider
);

const name = await resolverContract.name(reverseHash);
return name || null;
} catch (e) {
console.error("lookupAddress error", e);
return null;
}
};

// Get owner
const getDomainOwner = async (domain) => {
try {
const hash = namehash(domain);
const owner = await registry.owner(hash);

if (!owner || owner === AddressZero) return null;

return owner.toLowerCase();
} catch (e) {
console.error("owner error", e);
return null;
}
};

// Domain availability
const checkDomainAvailability = async (domain) => {
try {
const hash = namehash(domain);
const owner = await registry.owner(hash);
return owner === AddressZero;
} catch (e) {
console.error("availability error", e);
return false;
}
};

// Subdomain availability
const checkSubdomainAvailability = async (
domain,
subdomain
) => {
return checkDomainAvailability(`${subdomain}.${domain}`);
};

// RNS Hook
const useRns = () => {
const getAddressByRns = useCallback(async (name) => {
return await resolveRnsName(name);
}, []);

const getBitcoinAddressByRns = useCallback(async (name) => {
return await resolveBitcoinAddress(name);
}, []);

const getRnsName = useCallback(async (address) => {
return await lookupAddress(address);
}, []);

const getOwner = useCallback(async (domain) => {
return await getDomainOwner(domain);
}, []);

const checkAvailability = useCallback(async (domain) => {
return await checkDomainAvailability(domain);
}, []);

const checkSubdomain = useCallback(
async (domain, subdomain) => {
  return await checkSubdomainAvailability(domain, subdomain);
},
[]
);

return useMemo(
() => ({
  getAddressByRns,
  getBitcoinAddressByRns,
  getRnsName,
  getOwner,
  checkAvailability,
  checkSubdomain,
}),
[
  getAddressByRns,
  getBitcoinAddressByRns,
  getRnsName,
  getOwner,
  checkAvailability,
  checkSubdomain,
]
);
};

// UI Component
export default function App() {
const {
getAddressByRns,
getBitcoinAddressByRns,
getRnsName,
getOwner,
checkAvailability,
checkSubdomain,
} = useRns();

const [domain, setDomain] = useState("");
const [subdomain, setSubdomain] = useState("");
const [address, setAddress] = useState("");
const [result, setResult] = useState("");
const [owner, setOwner] = useState("");
const [loading, setLoading] = useState(false);

const wrap = async (fn) => {
setLoading(true);
setResult("");
setOwner("");
try {
  await fn();
} finally {
  setLoading(false);
}
};

return (
<div style={styles.container}>
  <div style={styles.card}>
    <h1 style={styles.heading}>Rootstock Name Service Lookup</h1>

    <input
      style={styles.input}
      value={domain}
      onChange={(e) => setDomain(e.target.value)}
      placeholder="Enter domain like testing.rsk"
    />

    <div style={styles.buttonGroup}>
      <button
        style={styles.button}
        disabled={loading}
        onClick={() =>
          wrap(async () => {
            const addr = await getAddressByRns(domain);
            setResult(addr || "No RSK address found");
          })
        }
      >
        Resolve RSK
      </button>

      <button
        style={styles.buttonAlt}
        disabled={loading}
        onClick={() =>
          wrap(async () => {
            const btc = await getBitcoinAddressByRns(domain);
            setResult(btc || "No Bitcoin address found");
          })
        }
      >
        Resolve BTC
      </button>
    </div>

    <button
      style={styles.buttonWide}
      disabled={loading}
      onClick={() =>
        wrap(async () => {
          const available = await checkAvailability(domain);
          setResult(
            available ? "✅ Domain is available" : "❌ Domain is taken"
          );
        })
      }
    >
      Check Availability
    </button>

    <div style={{ display: "flex", gap: "8px" }}>
      <input
        style={{ ...styles.input, flex: 1 }}
        value={subdomain}
        onChange={(e) => setSubdomain(e.target.value)}
        placeholder="Enter subdomain"
      />
      <button
        style={styles.buttonAlt}
        disabled={loading}
        onClick={() =>
          wrap(async () => {
            const available = await checkSubdomain(domain, subdomain);
            setResult(
              available
                ? "✅ Subdomain is available"
                : "❌ Subdomain is taken"
            );
          })
        }
      >
        Check Subdomain
      </button>
    </div>

    <button
      style={styles.buttonWide}
      disabled={loading}
      onClick={() =>
        wrap(async () => {
          const ownerAddr = await getOwner(domain);
          if (ownerAddr) {
            setOwner(ownerAddr);
            setResult("Owner found");
          } else {
            setResult("No owner found");
          }
        })
      }
    >
      Get Owner
    </button>

    {owner && (
      <div style={styles.ownerBox}>
        <strong>Owner:</strong> {owner}
      </div>
    )}

    <hr style={styles.divider} />

    <input
      style={styles.input}
      value={address}
      onChange={(e) => setAddress(e.target.value)}
      placeholder="Reverse lookup (address)"
    />

    <button
      style={styles.buttonWide}
      disabled={loading}
      onClick={() =>
        wrap(async () => {
          const name = await getRnsName(address);
          setResult(name || "No reverse entry found");
        })
      }
    >
      Reverse Lookup
    </button>

    <div style={styles.resultBox}>{loading ? "Loading..." : result}</div>
  </div>
</div>
);
}

10. Start Local Development Server

To preview this application, open your terminal and run the following command:

npm run start

This is how your UI should look:

RNS dApp

It should also function properly, as shown in the demo below:

Conclusion

In this guide, you've learned how to integrate RNS into your React app using ethers.js. You now understand how to:

Set up RNS with ethers.js providers and contracts
Handle overloaded contract functions properly
Create reusable functions for RNS operations
Build a custom React hook for RNS functionality
Implement a complete UI for RNS lookups and checks

This pattern can be easily extended or modified for your specific use case.

Sample dApp RNS Integration

Prerequisites

1. Project Setup

2. Change Index.js to React Dom

4. Initialize RNS

5. Utility Functions

6. Style for the UI

7. Core RNS Functions

a. Resolve a Rootstock Address

b. Resolve a Bitcoin Address

c. Reverse Lookup (Address to Name)

d. Get Domain Owner

e. Check Domain Availability

f. Check Subdomain Availability

6. Custom RNS Hook

8. Main Component

10. Start Local Development Server

Conclusion

Resources

このページ

もっと見る

フィードバック

Prerequisites​

1. Project Setup​

2. Change Index.js to React Dom​

4. Initialize RNS​

5. Utility Functions​

6. Style for the UI​

7. Core RNS Functions​

a. Resolve a Rootstock Address​

b. Resolve a Bitcoin Address​

c. Reverse Lookup (Address to Name)​

d. Get Domain Owner​

e. Check Domain Availability​

f. Check Subdomain Availability​

6. Custom RNS Hook​

8. Main Component​

10. Start Local Development Server​

Conclusion​

Resources​

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Prerequisites

1. Project Setup

2. Change Index.js to React Dom

4. Initialize RNS

5. Utility Functions

6. Style for the UI

7. Core RNS Functions

a. Resolve a Rootstock Address

b. Resolve a Bitcoin Address

c. Reverse Lookup (Address to Name)

d. Get Domain Owner

e. Check Domain Availability

f. Check Subdomain Availability

6. Custom RNS Hook

8. Main Component

10. Start Local Development Server

Conclusion

Resources