--- name: meshjs-cardano description: "MeshJS patterns: tx building, wallet connectors, script interactions. TypeScript\/JavaScript Cardano development." allowed-tools: - Read - Write user-invocable: true --- # meshjs-cardano ## When to use - Building Cardano dApps with MeshJS (TypeScript\/JavaScript) - Integrating CIP-30 wallet connectors - Transaction building in browser or Node.js ## Operating rules (must follow) - Confirm MeshJS version and environment (Next.js, Vite, Node) - Never request seed phrases or private keys - Handle wallet disconnects gracefully - Test on preprod before mainnet ## Setup ### Installation ```bash npm install @meshsdk\/core @meshsdk\/react # or yarn add @meshsdk\/core @meshsdk\/react ``` ### Provider setup ```typescript import { BlockfrostProvider } from '@meshsdk\/core'; const provider = new BlockfrostProvider(''); \/\/ or for preprod: const provider = new BlockfrostProvider('', 'preprod'); ``` ## Wallet connection (React) ```tsx import { CardanoWallet, useWallet } from '@meshsdk\/react'; function App() { const { connected, wallet } = useWallet(); return (

{connected &&

Connected!<\/p>} <\/div> ); } ``` ## Transaction building ### Simple ADA transfer ```typescript import { Transaction } from '@meshsdk\/core'; const tx = new Transaction({ initiator: wallet }) .sendLovelace( 'addr_test1qz...', '5000000' \/\/ 5 ADA ); const unsignedTx = await tx.build(); const signedTx = await wallet.signTx(unsignedTx); const txHash = await wallet.submitTx(signedTx); ``` ### With native tokens ```typescript const tx = new Transaction({ initiator: wallet }) .sendAssets( 'addr_test1qz...', [ { unit: 'lovelace', quantity: '2000000' }, { unit: '', quantity: '1' } ] ); ``` ### With metadata ```typescript const tx = new Transaction({ initiator: wallet }) .sendLovelace('addr_test1qz...', '1000000') .setMetadata(674, { msg: ['Hello from MeshJS'] }); ``` ## Script interactions ### Lock funds at script ```typescript import { Data } from '@meshsdk\/core'; const datum: Data = { alternative: 0, fields: [wallet.getPaymentAddress()] }; const tx = new Transaction({ initiator: wallet }) .sendLovelace( { address: scriptAddress, datum: { inline: datum } }, '5000000' ); ``` ### Spend from script ```typescript const tx = new Transaction({ initiator: wallet }) .redeemValue({ value: scriptUtxo, script: plutusScript, datum: datum, redeemer: { data: { alternative: 0, fields: [] } } }) .sendLovelace(recipientAddress, '4500000') .setCollateral([collateralUtxo]); ``` ## Examples ### Example: NFT minting **User request:** "Mint an NFT with MeshJS" **Response:** ```typescript import { ForgeScript, Transaction } from '@meshsdk\/core'; \/\/ Create minting script (time-locked) const { pubKeyHash } = wallet.getPaymentAddress(); const forgingScript = ForgeScript.withOneSignature(pubKeyHash); const assetMetadata = { name: 'My NFT', image: 'ipfs:\/\/...', mediaType: 'image\/png' }; const tx = new Transaction({ initiator: wallet }) .mintAsset( forgingScript, { assetName: 'MyNFT', assetQuantity: '1', metadata: assetMetadata, label: '721', recipient: wallet.getPaymentAddress() } ); const unsignedTx = await tx.build(); const signedTx = await wallet.signTx(unsignedTx); const txHash = await wallet.submitTx(signedTx); console.log('Minted:', txHash); ``` ### Example: Query UTxOs ```typescript import { BlockfrostProvider } from '@meshsdk\/core'; const provider = new BlockfrostProvider(''); \/\/ Get UTxOs for address const utxos = await provider.fetchAddressUTxOs(address); \/\/ Get UTxOs at script address const scriptUtxos = await provider.fetchAddressUTxOs(scriptAddress); \/\/ Filter by asset const nftUtxos = utxos.filter(utxo => utxo.output.amount.some(a => a.unit.includes(policyId)) ); ``` ## Common patterns ### Error handling ```typescript try { const txHash = await wallet.submitTx(signedTx); console.log('Success:', txHash); } catch (error) { if (error.message.includes('UTxO')) { console.log('UTxO issue - refresh and retry'); } else if (error.message.includes('collateral')) { console.log('Need ADA-only UTxO for collateral'); } } ``` ### Wallet state management ```typescript const { connected, connecting, disconnect, wallet, name } = useWallet(); \/\/ Check connection before operations if (!connected) { throw new Error('Wallet not connected'); } \/\/ Get network const network = await wallet.getNetworkId(); \/\/ 0 = testnet, 1 = mainnet ``` ## Safety \/ key handling - Never request seed phrases - Validate CIP-30 API availability - Handle disconnects gracefully - Show confirmation before signing ## References - `shared\/PRINCIPLES.md` - [MeshJS documentation](https:\/\/meshjs.dev) - [CIP-30 Wallet API](https:\/\/cips.cardano.org\/cips\/cip30\/)