medusa-store/docs/api/admin/code_samples/JavaScript/reservations/post.js

import Medusa from "@medusajs/medusa-js"
const medusa = new Medusa({ baseUrl: MEDUSA_BACKEND_URL, maxRetries: 3 })
// must be previously logged in or use api token
medusa.admin.reservations.create({
})
.then(({ reservations }) => {
  console.log(reservations.id);
});