global: snapshot

website/scripts/utils/price.js

@@ -0,0 +1,36 @@
+let _latest = /** @type {number | null} */ (null);
+
+/** @type {Set<(price: number) => void>} */
+const listeners = new Set();
+
+/** @param {(price: number) => void} callback */
+export function onPrice(callback) {
+  listeners.add(callback);
+  if (_latest !== null) callback(_latest);
+  return () => listeners.delete(callback);
+}
+
+export function latestPrice() {
+  return _latest;
+}
+
+/** @param {BrkClient} brk */
+export function initPrice(brk) {
+  async function poll() {
+    try {
+      const price = await brk.getLivePrice();
+      if (price !== _latest) {
+        _latest = price;
+        listeners.forEach((cb) => cb(price));
+      }
+    } catch (e) {
+      console.error("price poll:", e);
+    }
+  }
+
+  poll();
+  setInterval(poll, 5_000);
+  document.addEventListener("visibilitychange", () => {
+    !document.hidden && poll();
+  });
+}