JavaScript

These use the built-in fetch (Node.js 18+, or any browser - though see Security for why the key itself must never actually run in a browser; call your own backend from the browser, and put this code there).

A small client

const BASE_URL = "https://dev-api.theprioryshop.co.uk";
const API_KEY = process.env.EPOS_API_KEY; // never hardcode this

async function eposGet(path) {
  const res = await fetch(`${BASE_URL}${path}`, {
    headers: { Authorization: `Bearer ${API_KEY}` }
  });
  const body = await res.json();
  if (!res.ok) {
    const err = new Error(body.error?.message ?? "EPOS API request failed");
    err.code = body.error?.code;
    err.requestId = body.error?.requestId;
    err.status = res.status;
    throw err;
  }
  return body;
}

List products

const products = await eposGet("/v1/catalog/products?pageSize=20");
console.log(products.total, "products total,", products.rows.length, "on this page");

Get a single product

const product = await eposGet("/v1/catalog/products/clx1product000001");

List categories, promotions, inventory stock

const categories = await eposGet("/v1/catalog/categories");
const promotions = await eposGet("/v1/catalog/promotions");
const stock = await eposGet("/v1/inventory/stock?storeId=clx1store0000001");

Handle an error

try {
  await eposGet("/v1/catalog/products/does-not-exist");
} catch (err) {
  if (err.code === "not_found") {
    console.log("No such product");
  } else if (err.code === "rate_limited") {
    console.log("Back off and retry - see Rate Limits");
  } else {
    console.error(`EPOS API error ${err.code} (request ${err.requestId}):`, err.message);
  }
}

Paginate through every product

async function* allProducts() {
  let page = 1;
  while (true) {
    const { rows, totalPages } = await eposGet(`/v1/catalog/products?pageSize=100&page=${page}`);
    yield* rows;
    if (page >= totalPages) break;
    page += 1;
  }
}

for await (const product of allProducts()) {
  // ...
}

Incremental sync with updatedSince

const since = new URLSearchParams({ updatedSince: lastSyncedAt.toISOString() });
const changed = await eposGet(`/v1/catalog/products?${since}`);

See Catalog Sync for the full pattern.