import { polygonClient, restClient, websocketClient } from "@polygon.io/client-js";
const rest = restClient("API KEY");

// you can use the api now

rest.forex
  .previousClose("C:EURUSD")
  .then(/* your success handler */)
  .catch(/* your error handler*/);

import { restClient } from "@polygon.io/client-js";

const rest = restClient("api key");

rest.forex.previousClose("C:EURUSD").then(/* your success handler */);

import { referenceClient } from "@polygon.io/client-js";

const reference = referenceClient("api key");

reference.tickers().then(/* your success handler */);

import { websocketClient } from "@polygon.io/client-js";

const stocksWS = websocketClient("api key").stocks();

stocksWS.onmessage = ({data}) => {
  const [message] = JSON.parse(data);

  stocksWS.send('{"action":"subscribe", "params":"AM.MSFT,A.MSFT"}');

  switch (message.ev) {
    case "AM":
      // your trade message handler
      break;
    case "A":
      // your trade message handler
      break;
  }
};

stocksWS.send({ action: "subscribe", params: "T.MSFT" });