v149 · Clipboard · Lazy Read Demo

Lazy Read Demo

Step through the new lazy clipboard read: call read() to get available MIME types without fetching data, then click a type button to fetch only that format's data via getType().

Chrome 149 required for the lazy read behaviour. This demo requires clipboard read permission — Chrome will prompt. In older browsers, read() eagerly fetches all formats; you'll still see the same API, but the performance improvement won't apply.

live demo

Step 1: Copy something to your clipboard

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Step 2: Call clipboard.read() — types only, no data

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Step 3: Call getType() for a specific format

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code

// Step 1: read() — available types only, no data fetched
const items = await navigator.clipboard.read();

for (const item of items) {
  console.log('Available types:', item.types);
  // ['text/plain', 'text/html'] — data not yet loaded

  // Step 2: getType() — fetches ONLY this format
  if (item.types.includes('text/plain')) {
    const blob = await item.getType('text/plain');
    const text = await blob.text();
    console.log('text/plain data:', text);
    // Other formats were never read from the OS
  }
}

see also

implementation reference

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