Getting Started

Start by installing polkadot-api, and download the latest metadata from the chain you want to connect to and generate the types:

npm

npm i polkadot-api
 
# `papi add` is the command
# `dot` is the name we're giving to this chain (can be any JS variable name)
# `-n polkadot` specifies to download the metadata from the well-known chain polkadot
npx papi add dot -n polkadot
# Wait for the latest metadata to download, then generate the types:
npx papi

Now you can create a PolkadotClient instance with a provider of your choice and start interacting with the API:

1. Create the provider and Start the client

Smoldot

// `dot` is the name we gave to `npx papi add`
import { dot } from "@polkadot-api/descriptors"
import { createClient } from "polkadot-api"
import { getSmProvider } from "polkadot-api/sm-provider"
import { chainSpec } from "polkadot-api/chains/polkadot"
import { start } from "polkadot-api/smoldot"
 
// if interested, check out how to create a smoldot instance in a WebWorker
// http://papi.how/providers/sm#webworker
const smoldot = start()
const chain = await smoldot.addChain({ chainSpec })
 
// Connect to the polkadot relay chain.
const client = createClient(getSmProvider(chain))

2. Start consuming the client!

// With the `client`, you can get information such as subscribing to the last
// block to get the latest hash:
client.finalizedBlock$.subscribe((finalizedBlock) =>
  console.log(finalizedBlock.number, finalizedBlock.hash),
)
 
// To interact with the chain, you need to get the `TypedApi`, which includes
// all the types for every call in that chain:
const dotApi = client.getTypedApi(dot)
 
// get the value for an account
const accountInfo = await dotApi.query.System.Account.getValue(
  "16JGzEsi8gcySKjpmxHVrkLTHdFHodRepEz8n244gNZpr9J",
)