---
title: "KuCoin Auth Faster Hmac Sign JavaScript SDK Example | Siebly"
description: "KuCoin Auth faster hmac sign JavaScript example for the Siebly KuCoin SDK, covering exchange REST API and WebSocket integration, setup, and production SDK docs."
canonical: "https://siebly.io/examples/Kucoin/Auth/fasterHmacSign"
robots: "index,follow"
---

# KuCoin Auth Faster Hmac Sign JavaScript SDK Example

KuCoin Auth faster hmac sign JavaScript example for the Siebly KuCoin SDK, covering exchange REST API and WebSocket integration, setup, and production SDK docs.

**Path:** [Home](/) / [Examples](/examples) / [Kucoin](/examples/Kucoin) / [Auth](/examples/Kucoin/Auth) / [fasterHmacSign.ts](/examples/Kucoin/Auth/fasterHmacSign)

[View source on GitHub](https://github.com/sieblyio/crypto-api-examples/blob/master/examples/Kucoin/Auth/fasterHmacSign.ts)

[Open the KuCoin JavaScript SDK guide](/sdk/kucoin/javascript)

## fasterHmacSign.ts

```typescript
import { createHmac } from 'crypto';
import { DefaultLogger, SpotClient, WebsocketClient } from 'kucoin-api';

// import { DefaultLogger, SpotClient, WebsocketClient } from 'kucoin-api';

/**
 * Injecting a custom signMessage function.
 *
 * As of version 3.0.0 of the kucoin-api Node.js/TypeScript/JavaScript
 * SDK for Kucoin, the SDK uses the Web Crypto API for signing requests.
 * While it is compatible with Node and Browser environments, it is
 * slightly slower than using Node's native crypto module (only
 * available in backend Node environments).
 *
 * For latency sensitive users, you can inject the previous node crypto sign
 * method (or your own even faster implementation), if this change affects you.
 *
 * This example demonstrates how to inject a custom sign function, to achieve
 * the same peformance as seen before the Web Crypto API was introduced.
 *
 * For context on standard usage, the "signMessage" function is used:
 * - During every single API call
 * - After opening a new private WebSocket connection
 */

const apiKey = process.env.API_KEY_COM;
const apiSecret = process.env.API_SECRET_COM;
const apiPass = process.env.API_PASS_COM;

const restClient = new SpotClient({
  apiKey: apiKey,
  apiSecret: apiSecret,
  apiPassphrase: apiPass,
  /**
   * Overkill in almost every case, but if you need any optimisation available,
   * you can inject a faster sign mechanism such as node's native createHmac:
   */
  customSignMessageFn: async (message, secret) => {
    return createHmac('sha256', secret).update(message).digest('hex');
  },
});

// Optional, uncomment the "trace" override to log a lot more info about what the WS client is doing
const customLogger = {
  ...DefaultLogger,
  // trace: (...params) => console.log('trace', ...params),
};

const wsClient = new WebsocketClient(
  {
    apiKey: apiKey,
    apiSecret: apiSecret,
    apiPassphrase: apiPass,
    /**
     * Overkill in almost every case, but if you need any optimisation available,
     * you can inject a faster sign mechanism such as node's native createHmac:
     */
    customSignMessageFn: async (message, secret) => {
      return createHmac('sha256', secret).update(message).digest('hex');
    },
  },
  customLogger,
);

function setWsClientEventListeners(
  websocketClient: WebsocketClient,
  accountRef: string,
): Promise<void> {
  return new Promise((resolve) => {
    websocketClient.on('update', (data) => {
      console.log(new Date(), accountRef, 'data ', JSON.stringify(data));
      // console.log('raw message received ', JSON.stringify(data, null, 2));
    });

    websocketClient.on('open', (data) => {
      console.log(
        new Date(),
        accountRef,
        'connection opened open:',
        data.wsKey,
      );
    });
    websocketClient.on('response', (data) => {
      console.log(
        new Date(),
        accountRef,
        'log response: ',
        JSON.stringify(data, null, 2),
      );

      if (typeof data.req_id === 'string') {
        const topics = data.req_id.split(',');
        if (topics.length) {
          console.log(new Date(), accountRef, 'Subscribed to topics: ', topics);
          return resolve();
        }
      }
    });
    websocketClient.on('reconnect', ({ wsKey }) => {
      console.log(
        new Date(),
        accountRef,
        'ws automatically reconnecting.... ',
        wsKey,
      );
    });
    websocketClient.on('reconnected', (data) => {
      console.log(new Date(), accountRef, 'ws has reconnected ', data?.wsKey);
    });
    websocketClient.on('exception', (data) => {
      console.error(new Date(), accountRef, 'ws exception: ', data);
    });
  });
}

(async () => {
  try {
    const onSubscribed = setWsClientEventListeners(wsClient, 'testAccount1');

    wsClient.subscribe(
      [
        '/market/match:BTC-USDT',
        '/spotMarket/tradeOrders',
        '/spotMarket/tradeOrdersV2',
        '/account/balance',
        '/spotMarket/advancedOrders',
      ],
      'spotPrivateV1',
    );

    // Simple promise to ensure we're subscribed before trying anything else
    await onSubscribed;

    // Start trading
    const balResponse1 = await restClient.getBalances();
    console.log('balResponse1: ', JSON.stringify(balResponse1, null, 2));
  } catch (e) {
    console.error('request failed: ', e);
  }
})();
```