demo · v149

Format Cost Meter

The lazy-read change in Chrome 149 only matters if your clipboard contains expensive formats you don't need. Configure a realistic clipboard payload below, choose which formats your app actually reads, and see the estimated decode cost of eager-read (all formats) versus lazy-read (only the formats you request).

Clipboard preset:

Formats on clipboard (check = your app reads it)

Cost comparison

Eager (pre-149)

—

Lazy (Chrome 149+)

—

// Chrome 149+ — only read text/plain (one OS clipboard access)
const items = await navigator.clipboard.read();
for (const item of items) {
  // item.types available immediately at zero cost
  if (item.types.includes('text/plain')) {
    const blob = await item.getType('text/plain'); // ← one OS read
    const text = await blob.text();
    doSomethingWith(text);
    // text/html, image/png never fetched → no cost
  }
}

// Pre-149 — all formats read on navigator.clipboard.read()
// text/html decoded → image/png decoded → text/plain decoded
// even if only text/plain is used

implementation reference

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

see also

implementation reference