community-repo/contributions/tech/joystream-api/src/examples/general.ts

import { WsProvider, ApiPromise } from "@polkadot/api";
import { types } from "@joystream/types";
import { Vec } from "@polkadot/types";
import { Balance, EventRecord, Extrinsic, SignedBlock } from "@polkadot/types/interfaces";

async function main() {
    // Initialise the provider to connect to the local node
    const provider = new WsProvider('ws://127.0.0.1:9944');
      
    //If you want to play around on our staging network, go ahead and connect to this staging network instead.
    //const provider = new WsProvider('wss://testnet-rpc-2-singapore.joystream.org');

    // Create the API and wait until ready
    const api = await ApiPromise.create({ provider, types })

    // get finalized head of chain, as number and hash:
    const finalizedHeadNumber = await api.derive.chain.bestNumberFinalized()
    const finalizedHeadHash = await api.rpc.chain.getFinalizedHead()
    // get head of chain, as hash or number:
    const headNumber = await api.derive.chain.bestNumber()
    const headHash = await api.rpc.chain.getBlockHash(headNumber)

    console.log(
      `Finalized head of chain
      - as number: ${finalizedHeadNumber}
      - with hash: ${finalizedHeadHash}`
      )
    console.log(
      `Head of chain
      - as number: ${headNumber}
      - with hash: ${headHash}`
      )

    // get current issuance 
    const issuance = await api.query.balances.totalIssuance() as Balance
    console.log(`current issuance is: ${issuance.toNumber()}tJOY`)
    
    // get events in newest block:
    const events = await api.query.system.events() as Vec<EventRecord>;
    for (let { event } of events) {
      const section = event.section
      const method = event.method
      const data = event.data
      console.log("section",section)
      console.log("method",method)
      console.log("data",data.toHuman())
      console.log("")
    }

    // get extrinsics in finalized head block:
    const getLatestBlock = await api.rpc.chain.getBlock(finalizedHeadHash) as SignedBlock
    const extrinsics = getLatestBlock.block.extrinsics as Vec<Extrinsic>
    for (let i=0; i<extrinsics.length; i++) {
      const section = extrinsics[i].method.section
      const method = extrinsics[i].method.method
      console.log("section",section)
      console.log("method",method)
      console.log("")
      // get signer of extrinsics if applicable
      const signer = extrinsics[i].signer
      if (!signer.isEmpty) {
        console.log("signer",signer)
      }
    }
    
    api.disconnect()
}

main()