Profiler

// Server muss senden: Document-Policy: js-profiling
const heavyWork = () => {
  let sum = 0;
  for (let i = 0; i < 5e7; i++) sum += Math.sqrt(i);
  return sum;
};

const profileTask = async () => {
  if (!('Profiler' in window)) {
    console.warn('JS Self-Profiling API nicht verfügbar');
    return;
  }
  const profiler = new Profiler({ sampleInterval: 10, maxBufferSize: 10_000 });
  console.log('Tatsächliches Intervall:', profiler.sampleInterval, 'ms');

  heavyWork();

  const trace = await profiler.stop();
  console.log('Stichproben:', trace.samples.length);
  console.log('Frames:', trace.frames.length);
};

profileTask();

const topFunctions = (trace, limit = 5) => {
  const counts = new Map();
  for (const { stackId } of trace.samples) {
    if (stackId === undefined) continue; // Leerlauf, kein JS aktiv
    const { frameId } = trace.stacks[stackId]; // oberster Frame
    const frame = trace.frames[frameId];
    const name = frame.name || '(anonym)';
    const file = trace.resources[frame.resourceId] ?? '?';
    const key = `${name} @ ${file}:${frame.line ?? '?'}`;
    counts.set(key, (counts.get(key) ?? 0) + 1);
  }
  return [...counts].sort((a, b) => b[1] - a[1]).slice(0, limit);
};

const profiler = new Profiler({ sampleInterval: 10, maxBufferSize: 5000 });
// ... Anwendungscode läuft ...
setTimeout(async () => {
  const trace = await profiler.stop();
  console.table(topFunctions(trace));
}, 2000);

const profiler = new Profiler({ sampleInterval: 10, maxBufferSize: 1000 });

const finish = async () => {
  if (profiler.stopped) return;
  const trace = await profiler.stop();
  navigator.sendBeacon('/api/profiles', JSON.stringify({
    url: location.href,
    interval: profiler.sampleInterval,
    trace
  }));
};

// Puffer voll: Aufzeichnung endet, Daten trotzdem senden
profiler.addEventListener('samplebufferfull', () => {
  console.warn('Profiler-Puffer voll');
  finish();
});

window.addEventListener('load', () => setTimeout(finish, 0));