HTTP calls in series with delay between

SeriesCallWithDelay

/**
I wanted to call an endpoint updating an entity and I wanted to do it for 500 entities.
The API server had "rate limit" and I couldn't just use Promise.all 

I wrote this script just to call each update and have a 2 second delay between 
them to make sure API server would not block them

*/


import fetch from "node-fetch";
import { sessions } from "./data.js";

const bearerToken = ""

const updateSession = (sessionId) => {
  console.log(`updating session ${sessionId}`);
  return fetch(
    `https://www.url/${sessionId}`,
    {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
        Authorization: `Bearer ${bearerToken}`,
      },
    }
  );
};

const delay = () => {
  console.log(`Waiting: 2 seconds.`);
  return new Promise((resolve) => {
    setTimeout(() => {
      resolve("2");
    }, 2000);
  });
};

const startTime = Date.now();

const doNextPromise = async (sessionID) => {
  delay()
    .then((x) => {
      console.log(
        `Waited: ${x} seconds now calling the endpoint for updating session ${sessions[sessionID]}`
      );
      return updateSession(sessions[sessionID])
        .then((res) => {
          if (res.status !== 200) {
            throw `Error updating session ${sessions[sessionID]}: ${res.status}`;
          }
          return res.json();
        })
        .then((res) =>
          console.log(`Response: ${JSON.stringify(res)} for session ${sessions[sessionID]}`)
        )
        .catch((e) => console.log(`Error: ${e}`));
    })
    .then((res) => {
      sessionID++;
      if (sessionID < sessions.length) doNextPromise(sessionID);
      else console.log(`Total: ${(Date.now() - startTime) / 1000} seconds.`);
    });
};
doNextPromise(0);