Rate limits

const MAXIMUM_TRY_COUNT = 3;
const URL = 'https://api.hub2.io/balance;
const CONFIGURATION = {
  method: "GET",
  headers: {
    ApiKey: MY_API_KEY,
    MerchantId: MY_MERCHANT_ID,
  },
};

(function requestRetry(numberOfTries) {
  fetch(URL, CONFIGURATION)
    .then(() => {
      // code here
    })
    .catch((error) => {
      if (error?.response?.status === 429) {
        if (numberOfTries > MAXIMUM_TRY_COUNT) {
          throw error;
        }

        // Adding 1 second of grace delay
        const retryAfter: number = parseInt(response.headers['retry-after'], 10) + 1;
        await new Promise((resolve) => setTimeout(resolve, retryAfter));
        return requestRetry(numberOfTries + 1);
      }
    })
})(0);

// Using framework NestJS
import { HttpService } from "@nestjs/axios";
import { Injectable } from "@nestjs/common";
import { lastValueFrom } from "rxjs";

@Injectable()
export class HUB2Service {
  public static MAXIMUM_TRY_COUNT: number = 3;

  constructor(
    private readonly http: HttpService,
  ) {}

  async requestRetry(numberOfTries: number = 0): Promise<any> {
    const url = 'https://api.hub2.io/balance;
    const config = {
      headers: {
        ApiKey: MY_API_KEY,
        MerchantId: MY_MERCHANT_ID,
      },
    };
    try {
      const response = await lastValueFrom(this.http.post(url, {}, config));
    } catch (error) {
      if (error?.response?.status === 429) {
        if (numberOfTries > HUB2Service.MAXIMUM_TRY_COUNT) {
          throw error;
        }

        // Adding 1 second of grace delay
        const retryAfter: number = parseInt(response.headers['retry-after'], 10) + 1;
        await new Promise((resolve) => setTimeout(resolve, retryAfter));
        return this.requestRetry(numberOfTries + 1);
      }
    }
  }
}