polkadot-api

Features

• Light client first: built on top of the new JSON-RPC spec to fully leverage the potential of light-clients (i.e: smoldot).
• Delightful TypeScript support with types and docs generated from on-chain metadata.
• First class support for storage reads, constants, transactions, events and runtime-calls.
• Performant and lightweight: ships with multiple subpaths, so dApps don't bundle unnecessary assets.
• Uses native BigInt, instead of large BigNumber libraries
• Leverages dynamic imports to favour faster loading times.
• Promise-based and Observable-based APIs: use the one that best suit your needs and/or coding style.
• Use signers from your browser extension, or from a private key.
• Easy integration with PJS-based extensions.

... and a lot lot more.

Overview

smoldot.ts

import { startFromWorker } from "polkadot-api/smoldot/from-worker"
import SmWorker from "polkadot-api/smoldot/worker?worker"

// Starting smoldot on a Worker (strongly recommended)
export const smoldot = startFromWorker(new SmWorker())

// Alternatively, we could have smoldot running on the main-thread, e.g:
// import { start } from "polkadot-api/smoldot"
// export const smoldot = start()

main.ts

import { createClient } from "polkadot-api"
import { getSmProvider } from "polkadot-api/sm-provider"
import { polkadotTypes } from "@polkadot-api/descriptors"
import { smoldot } from "./smoldot"

// dynamically importing the chainSpec improves the performance of your dApp
const smoldotRelayChain = import("polkadot-api/chains/polkadot").then(
  ({ chainSpec }) => smoldot.addChain({ chainSpec }),
)

// getting a `JsonRpcProvider` from a `smoldot` chain.
const jsonRpcProvider = getSmProvider(smoldotRelayChain)

// we could also create a `JsonRpcProvider` from a WS connection, eg:
// const jsonRpcProvider = WsProvider("wss://some-rpc-endpoint.io")

const polkadotClient = createClient(jsonRpcProvider)

// logging blocks as they get finalized
polkadotClient.finalizedBlock$.subscribe((block) => {
  console.log(`#${block.number} - ${block.hash} - parentHash: ${block.parent}`)
})

// pulling the latest finalized block
const block = await polkadotClient.getFinalizedBlock()

// obtaining a delightfully typed interface from the descriptors
// previously generated from the metadata
const polkadotApi = polkadotClient.getTypedApi(polkadotTypes)

// presenting the transferrable amount of a given account
const {
  data: { free, frozen },
} = await polkadotApi.query.System.Account.getValue(
  "15oF4uVJwmo4TdGW7VfQxNLavjCXviqxT9S1MgbjMNHr6Sp5",
)
console.log(`Transferrable amount: ${free - frozen}`)

Documentation