[Feature Request] Built-in Auto-Scroll to Bottom Support

[phuctm97]

Summary

Add built-in support for "auto-scroll to bottom" behavior, commonly needed for chat interfaces, logs, and similar use cases.

Problem

Currently, implementing auto-scroll to bottom with dynamic item heights is unreliable:

1. scrollToIndex(lastIndex, { align: "end" }) often falls short with dynamic heights (v3.13.8 doesn't scroll all the way to the bottom correctly #1001)
2. No way to know when measurements are complete to safely scroll
3. "Sticky bottom" behavior (stay at bottom unless user scrolls up) requires significant custom logic

Use Case

Chat applications, terminal/log viewers, and any interface where:

• Items are dynamically sized
• New items are appended at the end
• User expects to see the latest item automatically
• User can scroll up without being forced back down

Proposed API

const virtualizer = useVirtualizer({
  count,
  getScrollElement: () => parentRef.current,
  estimateSize: () => 50,
  // New option:
  stickToBottom: true,
})

// New methods/properties
virtualizer.scrollToBottom()
virtualizer.isAtBottom

Related

• v3.13.8 doesn't scroll all the way to the bottom correctly #1001, how to scroll to bottom of a list at init #911, Any guidance on a reversed virtual list with dynamic elements? #195