Node.js script to check for CoWin Vaccine API and speak available slots

README.md

Queries the API every 5 seconds and uses the macOS say command to announce the available slots.

package.json

{
  "name": "vaccine",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "keywords": [],
  "author": "Param Aggarwal",
  "license": "ISC",
  "dependencies": {
    "superagent": "^6.1.0"
  }
}

vaccine.js

const superagent = require("superagent");
const { exec } = require("child_process");

const DISTRICT = 294; // find it on vaccineslot.in
const INTERVAL = 7; // seconds
const VACCINE = "COVAXIN"; // null: any or "COVISHIELD", "COVAXIN"
const WHEN = 1; // 0: today, 1: tomorrow

function run(command) {
  return new Promise(function (resolve, reject) {
    exec(command, (error, stdout) => {
      if (error) return reject(error);
      resolve(stdout.trim());
    });
  });
}

let announcements = Promise.resolve();
function check(date) {
  return superagent
    .get(
      "https://cdn-api.co-vin.in/api/v2/appointment/sessions/calendarByDistrict"
    )
    .query({
      district_id: DISTRICT,
      date: date,
    })
    .then((res) => {
      return res.body.centers
        .filter((c) => c.fee_type === "Paid")
        .map((c) => {
          return c.sessions
            .filter((s) => !VACCINE || s.vaccine === VACCINE)
            .filter((s) => s.available_capacity > 0)
            .map((s) => ({
              name: c.name,
              age: s.min_age_limit,
              dose1: s.available_capacity_dose1,
              dose2: s.available_capacity_dose2,
            }));
        })
        .flat();
    })
    .then((slots) => {
      if (slots.length) {
        slots.forEach((s) => {
          if (s.age === 18) {
            const message =
              s.dose1 + " slots available at " + s.name + " for " + s.age + "+";
            console.log(message);
            announcements = announcements.then(() => run(`say "${message}"`));
          } else if (s.age === 45) {
            const message =
              s.dose2 + " slots available at " + s.name + " for " + s.age + "+";
            console.log(message);
            announcements = announcements.then(() => run(`say "${message}"`));
          }
        });
      } else {
        console.log("Last checked at " + new Date().toLocaleString());
      }
    })
    .catch((err) => {
      console.error(err.status);
    })
    .then(() => {
      setTimeout(() => {
        check(date);
      }, INTERVAL * 1000);
    });
}

const date = new Date(Date.now() + WHEN * (1000 * 60 * 60 * 24))
  .toLocaleString()
  .slice(0, 10)
  .replace("/", "-")
  .replace("/", "-", "g");

console.log("Checking slots for " + date);
check(date);