@substrate/connect
An NPM package that offers an innovative way to interact with Substrate-based blockchains directly in your browser.
The primary implementation of the light-client provider for any Substrate-based chain.
## Using `@substrate/connect` for library authors
The `connect` package searches for a light client provider via the discovery protocol. If none is found, it will initiate a smoldot instance in the user's browser tab.
### Example Usage
To connect to a well-known chain ('polkadot', 'ksmcc3', 'westend2', 'rococo_v2_2'):
```js
import { createScClient, WellKnownChain } from "@substrate/connect"
const scClient = createScClient()
const chain = await scClient.addWellKnownChain(
WellKnownChain.westend2,
function jsonRpcCallback(response) {
console.log("response", response)
},
)
chain.sendJsonRpc(
'{"jsonrpc":"2.0","id":"1","method":"system_health","params":[]}',
)
```
To connect to a custom Substrate chain using its name and chainspec:
```js
import { createScClient } from "@substrate/connect"
import myJsonChainSpec from "./mySubstrateChainSpec.json"
const myChainSpec = JSON.stringify(myJsonChainSpec)
const scClient = createScClient()
const chain = await scClient.addChain(
myChainSpec,
function jsonRpcCallback(response) {
console.log("response", response)
},
)
chain.sendJsonRpc(
'{"jsonrpc":"2.0","id":"1","method":"system_health","params":[]}',
)
```
### Connecting to a Parachain
To connect to a parachain, first instantiate the relay chain it is connected to, then instantiate the parachain on the same relay chain. The following example connects to a parachain on the Westend test network:
```js
import { createScClient, WellKnownChain } from "@substrate/connect"
import jsonParachainSpec from "./myParaChainSpec.json"
const parachainSpec = JSON.stringify(jsonParachainSpec)
const scClient = createScClient()
const relayChain = await scClient.addWellKnownChain(WellKnownChain.westend2)
const parachain = await relayChain.addChain(
parachainSpec,
function jsonRpcCallback(response) {
console.log("response", response)
},
)
parachain.sendJsonRpc(
'{"jsonrpc":"2.0","id":"1","method":"system_health","params":[]}',
)
```
### PolkadotJs Example
```sh
yarn add @polkadot/rpc-provider
yarn add @polkadot/api
```
```ts
import { ScProvider } from "@polkadot/rpc-provider/substrate-connect"
import * as Sc from "@substrate/connect"
import { ApiPromise } from "@polkadot/api"
// Connect to polkadot relay chain
const provider = new ScProvider(Sc, Sc.WellKnownChain.polkadot)
await provider.connect()
const api = await ApiPromise.create({ provider })
// Connect to parachain
const provider2 = new ScProvider(Sc, Sc.WellKnownChain.people, provider)
await provider2.connect()
const api2 = await ApiPromise.create({ provider })
```
## Scripts
- `pnpm test` to run the unit tests
- `pnpm build` to build @substrate-connect
- `pnpm lint` to run linter for @substrate-connect