otterscan/src/Home.tsx

import React, { useState, useEffect } from "react";
import { NavLink, useHistory } from "react-router-dom";
import { ethers } from "ethers";
import Logo from "./Logo";
import Timestamp from "./components/Timestamp";
import { provider } from "./ethersconfig";

const Home: React.FC = () => {
  const [search, setSearch] = useState<string>();
  const [canSubmit, setCanSubmit] = useState<boolean>(false);
  const history = useHistory();

  const handleChange: React.ChangeEventHandler<HTMLInputElement> = (e) => {
    setCanSubmit(e.target.value.trim().length > 0);
    setSearch(e.target.value.trim());
  };

  const handleSubmit: React.FormEventHandler<HTMLFormElement> = (e) => {
    e.preventDefault();
    if (!canSubmit) {
      return;
    }

    history.push(`/search?q=${search}`);
  };

  const [latestBlock, setLatestBlock] = useState<ethers.providers.Block>();
  useEffect(() => {
    const readLatestBlock = async () => {
      const blockNum = await provider.getBlockNumber();
      const _raw = await provider.send("erigon_getHeaderByNumber", [blockNum]);
      const _block = provider.formatter.block(_raw);
      setLatestBlock(_block);
    };
    readLatestBlock();

    const listener = async (blockNumber: number) => {
      const _raw = await provider.send("erigon_getHeaderByNumber", [
        blockNumber,
      ]);
      const _block = provider.formatter.block(_raw);
      setLatestBlock(_block);
    };

    provider.on("block", listener);
    return () => {
      provider.removeListener("block", listener);
    };
  }, []);

  document.title = "Home | Otterscan";

  return (
    <div className="h-screen flex m-auto">
      <div className="flex flex-col m-auto">
        <Logo />
        <form
          className="flex flex-col m-auto"
          onSubmit={handleSubmit}
          autoComplete="off"
          spellCheck={false}
        >
          <input
            className="w-full border rounded focus:outline-none px-2 py-1 mb-10"
            type="text"
            size={50}
            placeholder="Search by address / txn hash / block number"
            onChange={handleChange}
            autoFocus
          ></input>
          <button
            className="mx-auto px-3 py-1 mb-10 rounded bg-gray-100 hover:bg-gray-200 focus:outline-none"
            type="submit"
          >
            Search
          </button>
          {latestBlock && (
            <NavLink
              className="mx-auto flex flex-col items-center space-y-1 mt-5 text-sm text-gray-500 hover:text-link-blue"
              to={`/block/${latestBlock.number}`}
            >
              <div>
                Latest block: {ethers.utils.commify(latestBlock.number)}
              </div>
              <Timestamp value={latestBlock.timestamp} />
            </NavLink>
          )}
        </form>
      </div>
    </div>
  );
};

export default React.memo(Home);