Query pending txs

frontrun.ts

import { decodeTxRaw } from "@cosmjs/proto-signing";
import * as injProto from "@injectivelabs/core-proto-ts";
import { GasFee } from "@injectivelabs/sdk-ts";
import { MsgType } from "@injectivelabs/ts-types";

const typeMap = Object.fromEntries(Object.entries(MsgType).map(([k, v]) => ["/" + v, k]));

type TxType = keyof typeof MsgType;

const findType = (obj: any, type: string) => {
  if (typeof obj !== "object") return;
  const msg = obj[type];
  if (msg && msg.decode) return msg;
  for (const subObj of Object.values(obj)) {
    const find = findType(subObj, type);
    if (find) return find;
  }
};

const decodeProto = (msg: { typeUrl: string; value: Uint8Array }) => {
  const type = typeMap[msg.typeUrl];
  if (type) {
    const obj = findType(injProto, type);
    if (obj) {
      const res = obj.decode(msg.value);
      res.type = type;
      if (res.msgs) {
        res.msgs = res.msgs.map(decodeProto);
      }
      return res;
    }
  }
};

export type FrontRunInfo = {
  fee: GasFee;
  msgs: object[];
};

class FrontRunClient {
  public readonly rpc: string;
  constructor(rpc: string) {
    this.rpc = rpc.replace(/\/+$/, "");
  }

  async queryPendingTxs(types: TxType[] = [], limit = 30): Promise<FrontRunInfo[]> {
    const { result } = await fetch(`${this.rpc}/unconfirmed_txs?limit=${limit}`).then((res) => res.json());
    return result.txs.map((txRaw: string) => {
      const tx = decodeTxRaw(Buffer.from(txRaw, "base64"));
      const { amount, gasLimit, ...rest } = tx.authInfo.fee;
      const info: FrontRunInfo = {
        fee: {
          amounts: amount,
          gasLimit: gasLimit.toNumber(),
          ...rest
        },
        msgs: tx.body.messages
          .filter((msg) => {
            if (!types || types.length == 0) return true;
            const type = typeMap[msg.typeUrl] as TxType;
            return types.includes(type);
          })
          .map(decodeProto)
      };

      return info;
    });
  }
}

(async () => {
  const frontRunClient = new FrontRunClient("https://rpc-injective.keplr.app");
  const pendingTxs = await frontRunClient.queryPendingTxs(["MsgBatchUpdateOrders"]);
  const maxGasLimit = Math.max(...pendingTxs.map((tx) => tx.fee.gasLimit));
  console.log(maxGasLimit);
})();