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Stacks Connect

Stacks Connect Reference Discord Support

Stacks Connect is a frontend library that allows developers to build Stacks-ready web applications.

What are the main things you can do with Stacks Connect?

  • 📸 Prompt a user to sign transactions with their Stacks wallet
  • 🛂 Provide the web-app with the user's Stacks and Bitcoin addresses

Start from a template with Stacks Connect included​

Get started from a frontend template, by running the following command:

npm create stacks

After you have your project set up, you can start using Stacks Connect. Jump ahead to Interacting with the wallet to see more code examples.

Manually add Stacks Connect to your project​

1. Add the dependency​

Add the @stacks/connect dependency to your project using your favorite package manager.

npm install @stacks/connect

2. Creating AppConfig and UserSession​

Add a reusable UserSession instance to your project. This will allow your website to store authentication state in localStorage.

/* ./userSession.js */
import { AppConfig, UserSession } from '@stacks/connect';

const appConfig = new AppConfig(['store_write', 'publish_data']);
export const userSession = new UserSession({ appConfig }); // we will use this export from other files

3. Interacting with the wallet​

"Connect" aka authentication (showConnect)​

Connecting the wallet is a very simple form of authentication. This process gives the web-app information about a wallet account (selected by the user).

The snippet below lets your web-app trigger the wallet to open and authenticate an account. If no wallet is installed, an informational modal will be displayed in the web-app.

import { showConnect } from '@stacks/connect';
import { userSession } from './userSession';

const myAppName = 'My Stacks Web-App'; // shown in wallet pop-up
const myAppIcon = window.location.origin + '/my_logo.png'; // shown in wallet pop-up

showConnect({
  userSession, // `userSession` from previous step, to access storage
  appDetails: {
    name: myAppName,
    icon: myAppIcon,
  },
  onFinish: () => {
    window.location.reload(); // WHEN user confirms pop-up
  },
  onCancel: () => {
    console.log('oops'); // WHEN user cancels/closes pop-up
  },
});

Sending STX (openSTXTransfer)​

Sending STX tokens is also possible through web-apps interacting with a user's wallet.

The snippet below will open the wallet to confirm and broadcast a smart-contract transaction. Here, we are sending 10000 micro-STX tokens to a recipient address.

import { openSTXTransfer } from '@stacks/connect';
import { StacksTestnet } from '@stacks/network';
import { AnchorMode, PostConditionMode } from '@stacks/transactions';
import { userSession } from './userSession';

openSTXTransfer({
  network: new StacksTestnet(), // which network to use; use `new StacksMainnet()` for mainnet
  anchorMode: AnchorMode.Any, // which type of block the tx should be mined in

  recipient: 'ST39MJ145BR6S8C315AG2BD61SJ16E208P1FDK3AK', // which address we are sending to
  amount: 10000, // tokens, denominated in micro-STX
  memo: 'Nr. 1337', // optional; a memo to help identify the tx

  onFinish: response => {
    // WHEN user confirms pop-up
    console.log(response.txid); // the response includes the txid of the transaction
  },
  onCancel: () => {
    // WHEN user cancels/closes pop-up
    console.log('User canceled');
  },
});

Calling Smart-Contracts (openContractCall)​

Calling smart-contracts lets users interact with the blockchain through transactions.

The snippet below will open the wallet to confirm and broadcast a smart-contract transaction. Here, we are passing our pick Alice to an imaginary deployed voting smart-contract.

import { openContractCall } from '@stacks/connect';
import { StacksTestnet } from '@stacks/network';
import { AnchorMode, PostConditionMode, stringUtf8CV } from '@stacks/transactions';
import { userSession } from './userSession';

const pick = stringUtf8CV('Alice');

openContractCall({
  network: new StacksTestnet(),
  anchorMode: AnchorMode.Any, // which type of block the tx should be mined in

  contractAddress: 'ST39MJ145BR6S8C315AG2BD61SJ16E208P1FDK3AK',
  contractName: 'example-contract',
  functionName: 'vote',
  functionArgs: [pick],

  postConditionMode: PostConditionMode.Deny, // whether the tx should fail when unexpected assets are transferred
  postConditions: [], // for an example using post-conditions, see next example

  onFinish: response => {
    // WHEN user confirms pop-up
  },
  onCancel: () => {
    // WHEN user cancels/closes pop-up
  },
});

Sending transactions with post-conditions (openContractCall)​

Consider the example above. Using post-conditions, a feature of the Stacks blockchain, we can ensure something happened after a transaction. Here, we could ensure that the recipient indeed receives a certain amount of STX.

import {
  PostConditionMode,
  FungibleConditionCode,
  makeStandardSTXPostCondition,
} from '@stacks/transactions';

// this post-condition ensures that our recipient receives at least 5000 STX tokens
const myPostCondition = makeStandardSTXPostCondition(
  'ST39MJ145BR6S8C315AG2BD61SJ16E208P1FDK3AK', // address of recipient
  FungibleConditionCode.GreaterEqual, // comparator
  5000000000 // relative amount to previous balance (denoted in micro-STX)
);

// passing to `openContractCall` options, e.g. modifying our previous example ...
  postConditionMode: PostConditionMode.Deny, // whether the tx should fail when unexpected assets are transferred
  postConditions: [ myPostCondition ],
// ...

For more examples on constructing different kinds of post-conditions read the Post-Conditions Guide of Stacks.js.

Post-Condition Modes​

If post-conditions postConditions: [ ... ] are specified, they will ALWAYS be checked by blockchain nodes. If ANY conditions fails, the transaction will fail.

The Post-Condition Mode only relates to transfers of assets, which were not specified in the postConditions.

  • PostConditionMode.Deny will fail the transaction if any unspecified assets are transferred
  • PostConditionMode.Allow will allow unspecified assets to be transferred
  • In both cases, all postConditions will be checked