const { ethers } = require("ethers");

const endpoint =
  "YOUR_CHAINSTACK_ENDPOINT";

async function getPastBlocksBatch() {
  const provider = new ethers.JsonRpcProvider(endpoint);
  const latestBlockNumber = await provider.getBlockNumber();
  const startTime = Date.now();

  const pastBlocksPromises = Array.from(
    { length: 20 },
    (_, i) => latestBlockNumber - i
  ).map((blockNumber) => {
    return {
      id: blockNumber,
      jsonrpc: "2.0",
      method: "eth_getBlockByNumber",
      params: [ethers.toQuantity(blockNumber), false],
    };
  });

  const pastBlocks = await provider._send(pastBlocksPromises);

  const endTime = Date.now();
  const executionTime = endTime - startTime;

  console.log(`Execution batch time: ${executionTime} ms`);

  return pastBlocks;
}

getPastBlocksBatch().then((blocks) => {
  blocks.forEach((blockResult) => {
    if (blockResult.error) {
      console.log(
        `Error fetching block: ${blockResult.error}`,
        blockResult.error
      );
    } else {
      const block = blockResult.result;
      console.log(`Block number: ${parseInt(block.number, 16)}`);
      console.log(`Block hash: ${block.hash}`);
      console.log("-------------------------");
    }
  });
});

Execution batch time: 786 ms

Block number: 17787188
Block hash: 0x57c181e5bf88645e448a89ce86a6e2d89f70b18dde2b898ad0da744aa958aac0
-------------------------
Block number: 17787187
Block hash: 0xbe95b9bfed0eaf4105d12db3ea2d4445a6115e3dcc4e36cf1a713c4c5534bef2
-------------------------
Block number: 17787186
Block hash: 0xab086d364d4a2b74eb80b7bdc1f8929543e2e6885c1ee70d478247bda2ea1deb
-------------------------
Block number: 17787185
Block hash: 0x56f0fe238baf6a2b7b22ac78d99fff0224cd134cee5271f62be6503f2db94880
-------------------------
Block number: 17787184
Block hash: 0xdf67e5391456c75598210486e10707c9e14890e44cf967e3bc6365844032fae3
-------------------------
Block number: 17787183
Block hash: 0x74aa07e0aeb2990a52ec729002a766bbdbf96981edbd17586462e0c7f0db8401
-------------------------
Block number: 17787182
Block hash: 0x66bb9f0e74c556951b11adad3a3e0103abaf3241edf029212df1fd0fed9fe007
-------------------------
Block number: 17787181
Block hash: 0x0f95564e18819455bff61fc453c11aa58f21be4fbe62d9638dfa08624003d797
-------------------------
Block number: 17787180
Block hash: 0x4a2108025f87b4505787e664bb23812cdd7d9cb32567c7a6ac930a9f54cf9bb9
-------------------------
Block number: 17787179
Block hash: 0x65c8b1e8032add2e0a7b15c635dff6196cb72f7b97576a66876993c75583e4c8
-------------------------
Block number: 17787178
Block hash: 0xc00a091e71f41c6722730be8496362f68c760193a34d014d45d46da6eae660ef
-------------------------
Block number: 17787177
Block hash: 0x63f870742f7c4dae5444e338d2f817a8a04d334e9026b99df7e05ede8e41700b
-------------------------
Block number: 17787176
Block hash: 0x83190bc285bca53f2f98b3d6f0773183495928e4c9c7edfba6bb88865cdf1f17
-------------------------
Block number: 17787175
Block hash: 0xe3ae69abefd5f06339f0399c46c5bf4c7622378950923e6f0fb2007e74d670cb
-------------------------
Block number: 17787174
Block hash: 0xb5b4ea9c910236710cc5d70ba29159859f2dcc901ef6abbd653db5d9dc1fe8dc
-------------------------
Block number: 17787173
Block hash: 0x45abcaf6ef8dee46444ec4065644d730ad7b962ea605672a7ed535e850006a92
-------------------------
Block number: 17787172
Block hash: 0xab592f9f9623e1be922374a79c22802570cbcae49bdc0928bffc98780a540752
-------------------------
Block number: 17787171
Block hash: 0x98ab72cc36bff5715cc1471ae7f8459905e3c5fb9cd40520234e01714a2a0a3d
-------------------------
Block number: 17787170
Block hash: 0x2d4045355ad94b0c70c5c6cc6df49ea43641d10f22f0ae61780b40f13f0b05e0
-------------------------
Block number: 17787169
Block hash: 0x5807d23bb5719584605990083bf6fd189971d7e1c6b797200fe6e21df1c70e61
-------------------------