TypeScript

npm install openpx

import { Exchange } from "openpx";

class Exchange {
  constructor(id: string, config: any);
  websocket(): WebSocket;
  get id(): string;
  get name(): string;
  describe(): any;

  // Auto-paginates and returns every market.
  fetchMarkets(): Promise<any>;
  fetchMarket(marketId: string): Promise<any>;

  createOrder(
    marketId: string,
    outcome: string,
    side: string,
    price: number,
    size: number,
    params?: any,
  ): Promise<any>;
  cancelOrder(orderId: string, marketId?: string): Promise<any>;
  fetchOrder(orderId: string, marketId?: string): Promise<any>;
  fetchOpenOrders(marketId?: string): Promise<any>;

  fetchPositions(marketId?: string): Promise<any>;
  fetchBalance(): Promise<any>;

  fetchOrderbook(
    marketId: string,
    outcome?: string,
    tokenId?: string,
  ): Promise<any>;
  fetchFills(marketId?: string, limit?: number): Promise<any>;

  fetchPriceHistory(
    marketId: string,
    interval: string,
    outcome?: string,
    tokenId?: string,
    conditionId?: string,
    startTs?: number,
    endTs?: number,
  ): Promise<any>;

  fetchTrades(
    marketId: string,
    marketRef?: string,
    outcome?: string,
    tokenId?: string,
    startTs?: number,
    endTs?: number,
    limit?: number,
    cursor?: string,
  ): Promise<any>;

  fetchOrderbookHistory(
    marketId: string,
    tokenId?: string,
    startTs?: number,
    endTs?: number,
    limit?: number,
    cursor?: string,
  ): Promise<any>;
}

class WebSocket {
  constructor(id: string, config: any);
  connect(): Promise<void>;
  disconnect(): Promise<void>;
  subscribe(marketId: string): Promise<void>;
  unsubscribe(marketId: string): Promise<void>;
  get state(): string;

  // Resolves when the stream ends. Callback receives each update.
  onOrderbookUpdate(
    marketId: string,
    callback: (err: Error | null, update: any) => void,
  ): Promise<void>;

  onActivityUpdate(
    marketId: string,
    callback: (err: Error | null, event: any) => void,
  ): Promise<void>;
}

import { Exchange } from "openpx";

const ex = new Exchange("polymarket", {
  private_key: process.env.POLYMARKET_PRIVATE_KEY!,
  funder: process.env.POLYMARKET_FUNDER!,
});

const ws = ex.websocket();
await ws.connect();
await ws.subscribe("0x…token_id");

await ws.onOrderbookUpdate("0x…token_id", (err, update) => {
  if (err) return console.error(err);
  // update.kind is "Snapshot" | "Delta" | "Clear" | "Trade" | "Fill"
});