v148 · Performance · Resource Timing

MIME Type Performance Analyzer

Fetches resources of 8 different types and groups them by contentType from PerformanceResourceTiming. See average load times, transfer vs decoded size ratios, cache hit rates, and unexpected content type flags.

API probe: PerformanceResourceTiming.contentType (Chrome 148+)
Checking…
Select a probe set, then fetch same-origin resources served by the demo route. The table compares the server's Content-Type header with the browser's PerformanceResourceTiming.contentType.
0
Resources
0
MIME types
Avg load (ms)
0
Flagged

Avg load time by MIME type (ms)

Run analysis to see data.

Transfer size vs decoded size (KB)

Run analysis to see data.
Resource Detail Table
URL contentType Response header Transfer Decoded Load (ms) Cache Flag
Run analysis above to load resource data.
Resource Audit — Unexpected Content Types
No audit data yet. Run analysis first.
Live PerformanceObserver Log
--:--:--PerformanceObserver watching for "resource" entries…

how it works

const po = new PerformanceObserver(list => {
  list.getEntries().forEach(entry => {
    console.log(
      entry.name,          // URL
      entry.contentType,   // "text/javascript" ← NEW in Chrome 148
      entry.transferSize,  // bytes on wire
      entry.decodedBodySize
    );
  });
});
po.observe({ type: 'resource', buffered: true });

references

implementation reference

Need the exact API surface, compatibility boundaries, errors, lifecycle, and source links? Read the matching gendn reference ↗