https://pressthink.org/j/rosen-archive/frontend/utils/perfMark.js?v=3.8.36

1// Performance marks for the debug-flagged data-load timing (#280).
2//
3// No-ops unless `localStorage.jrda_debug === '1'` (the #170 debug toggle), so
4// nothing here runs in production. Every call is wrapped in try/catch: the
5// Performance API and localStorage can throw in privacy modes or under a
6// storage policy, and a throw here must never break the data-load path these
7// marks wrap (fetchCoreData's fail-loud contract, #290).
8
9const enabled = (() => {
10  try {
11    return typeof localStorage !== 'undefined'
12      && localStorage.getItem('jrda_debug') === '1'
13      && typeof performance !== 'undefined'
14      && typeof performance.mark === 'function';
15  } catch {
16    return false;
17  }
18})();
19
20export const perfMark = (name) => {
21  if (!enabled) return;
22  try {
23    performance.mark(name);
24  } catch {
25    // Performance API unavailable or name invalid -- timing is best-effort.
26  }
27};
28
29export const perfMeasure = (name, startMark, endMark) => {
30  if (!enabled) return;
31  try {
32    performance.measure(name, startMark, endMark);
33  } catch {
34    // A missing start/end mark throws; skip rather than break the caller.
35  }
36};