TanStack/virtual @tanstack/virtual-core@3.13.14

on GitHub

Patch Changes

• Fix: Correct lane assignments when lane count changes dynamically (#1095)

  Fixed a critical bug where changing the number of lanes dynamically would cause layout breakage with incorrect lane assignments. When the lane count changed (e.g., from 3 to 2 columns in a responsive masonry layout), some virtual items would retain their old lane numbers, causing out-of-bounds errors and broken layouts.

  Root Cause: After clearing measurements cache on lane change, the virtualizer was incorrectly restoring data from initialMeasurementsCache, which contained stale lane assignments from the previous lane count.

  Fix: Skip initialMeasurementsCache restoration during lane transitions by checking the lanesSettling flag. This ensures all measurements are recalculated with correct lane assignments for the new lane count.

  Before:

  // With lanes = 2
  virtualItems.forEach((item) => {
    columns[item.lane].push(item) // ❌ Error: item.lane could be 3
  })

  After:

  // With lanes = 2
  virtualItems.forEach((item) => {
    columns[item.lane].push(item) // ✅ item.lane is always 0 or 1
  })

  This fix is essential for responsive masonry layouts where column count changes based on viewport width. No performance impact as it only affects the lane change transition path.