API Reference: sd-metrics

The sd-metrics script evaluates the physical hardware and exposes the results via an asynchronous JavaScript API.

Because modern Single Page Applications (SPAs) and ad scripts often load concurrently with third-party libraries, the Impulse Engine provides robust listener methods (.on, .once, .get) to guarantee you never encounter a race condition or an undefined variable.

Metric names

• AdTech Variables: ìnventory_tier, ìnventory_tier. Have a look to AdTech metrics references for more details.
• Engineering Metrics: bdp, mdc, air. Have a look to Engineering metrics references for more details.

Metric Methods

Each metric object exposes three methods to handle data retrieval based on your application's architecture.

1. .get()

Returns a standard JavaScript Promise that resolves with the metric's value as soon as the hardware evaluation is complete. Ideal for async/await workflows.

Example:

async function initializeApp() {
  try {
    const bdpScore = await window.sd.bdp.get();
    
    if (bdpScore > 4.0) {
      await loadHeavy3dModel();
    }
  } catch (error) {
    console.warn('Hardware profiling timeout, falling back to safe UI.');
  }
}

2. .once(callback)

Fires the provided callback function exactly one time when the metric is resolved. This is highly recommended for triggering initial load logic (like setting Google Ad Manager targeting).

Example:

window.sd.inventory_tier.once((tier) => {
  // Push to Ad Server immediately upon resolution
  googletag.cmd.push(function() {
    googletag.pubads().setTargeting('sd_inventory_tier', tier.toString());
  });
});

3. .on(callback)

Subscribes a listener to the metric. While hardware limits rarely change during a single page view, this method is useful for frameworks like React or Vue where you may want to bind the metric to a reactive state variable that persists across client-side navigations.

Example:

// React useEffect hook
useEffect(() => {
  if (window.sd) {
    window.sd.mdc.on((threads) => {
      setWorkerCount(threads);
    });
  }
}, []);