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docs(vue-virtual): use onUpdated to prevent scroll jumping #1125

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docs(vue-virtual): use `onUpdated` for `measureElement` to prevent sc…
Mini-ghost Feb 17, 2026
893ad75
chore: run lint
Mini-ghost Feb 17, 2026
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19 changes: 10 additions & 9 deletions examples/vue/dynamic/src/components/ColumnVirtualizerDynamic.vue
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Original file line number Diff line number Diff line change
Expand Up @@ -15,7 +15,7 @@
v-for="virtualColumn in virtualColumns"
:key="virtualColumn.key"
:data-index="virtualColumn.index"
:ref="measureElement"
ref="virtualItemEls"
:class="virtualColumn.index % 2 ? 'ListItemOdd' : 'ListItemEven'"
:style="{
position: 'absolute',
Expand All @@ -35,7 +35,7 @@
</template>

<script setup lang="ts">
import { ref, computed, type VNodeRef } from 'vue'
import { computed, onMounted, onUpdated, ref, shallowRef } from 'vue'
import { useVirtualizer } from '@tanstack/vue-virtual'
import { generateSentences } from './utils'

Expand All @@ -54,13 +54,14 @@ const virtualColumns = computed(() => columnVirtualizer.value.getVirtualItems())

const totalSize = computed(() => columnVirtualizer.value.getTotalSize())

const measureElement = (el) => {
if (!el) {
return
}
const virtualItemEls = shallowRef([])
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Copilot AI Mar 12, 2026

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shallowRef([]) with an empty array literal infers never[] in TypeScript, which can make el in forEach be never and cause type errors when passing it to measureElement. Consider explicitly typing virtualItemEls (e.g. as an array of HTMLElement | null).

Suggested change
const virtualItemEls = shallowRef([])
const virtualItemEls = shallowRef<(HTMLElement | null)[]>([])

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columnVirtualizer.value.measureElement(el)

return undefined
function measureAll() {
virtualItemEls.value.forEach((el) => {
if (el) columnVirtualizer.value.measureElement(el)
})
Comment on lines +59 to +62
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@piecyk piecyk Mar 12, 2026

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Calling measureElement(null) first ensures stale elements from previous renders are cleaned up before re-registering the current ones. Without it, if virtual items get recycled (scrolling removes old DOM nodes), those old nodes may linger in the cache until the ResizeObserver's own callback eventually notices they're disconnected. Adding the null call makes cleanup immediate and deterministic.

Suggested change
function measureAll() {
virtualItemEls.value.forEach((el) => {
if (el) columnVirtualizer.value.measureElement(el)
})
function measureAll() {
rowVirtualizer.value.measureElement(null)
virtualItemEls.value.forEach((el) => {
if (el) rowVirtualizer.value.measureElement(el)
})

}
Comment on lines +59 to 63
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measureAll never calls columnVirtualizer.value.measureElement(null). In @tanstack/virtual-core, passing null is what triggers cleanup of disconnected nodes (unobserving/removing stale entries from elementsCache). Without that, columns that scroll out/unmount can remain observed/retained. Consider calling measureElement(null) once per update (or using a callback ref that forwards null on unmount) in addition to measuring the current elements.

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onMounted(measureAll)
onUpdated(measureAll)
</script>
23 changes: 12 additions & 11 deletions examples/vue/dynamic/src/components/GridVirtualizerDynamic.vue
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Original file line number Diff line number Diff line change
Expand Up @@ -9,7 +9,7 @@
<template v-for="virtualRow in virtualRows" :key="virtualRow.key">
<div
:data-index="virtualRow.index"
:ref="measureElement"
ref="virtualItemEls"
:style="{
position: 'absolute',
top: 0,
Expand Down Expand Up @@ -47,9 +47,9 @@
</template>

<script setup lang="ts">
import { ref, computed, onMounted, type VNodeRef } from 'vue'
import { useWindowVirtualizer, useVirtualizer } from '@tanstack/vue-virtual'
import { generateData, generateColumns } from './utils'
import { computed, onMounted, onUpdated, ref, shallowRef } from 'vue'
import { useVirtualizer, useWindowVirtualizer } from '@tanstack/vue-virtual'
import { generateColumns, generateData } from './utils'

const columns = generateColumns(30)
const data = generateData(columns)
Expand Down Expand Up @@ -103,13 +103,14 @@ const width = computed(() => {
: [0, 0]
})

const measureElement = (el) => {
if (!el) {
return
}

rowVirtualizer.value.measureElement(el)
const virtualItemEls = shallowRef([])
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shallowRef([]) with an empty array literal infers never[] in TypeScript, which can make el in forEach be never and cause type errors when passing it to measureElement. Consider explicitly typing virtualItemEls (e.g. as an array of HTMLElement | null).

Suggested change
const virtualItemEls = shallowRef([])
const virtualItemEls = shallowRef<(HTMLElement | null)[]>([])

Copilot uses AI. Check for mistakes.

return undefined
function measureAll() {
virtualItemEls.value.forEach((el) => {
if (el) rowVirtualizer.value.measureElement(el)
})
}
Comment on lines +108 to 112
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measureAll never calls rowVirtualizer.value.measureElement(null). In @tanstack/virtual-core, passing null is what triggers cleanup of disconnected nodes (unobserving/removing stale entries from elementsCache). Without that, rows that scroll out/unmount can remain observed/retained. Consider calling measureElement(null) once per update (or using a callback ref that forwards null on unmount) in addition to measuring the current elements.

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onMounted(measureAll)
onUpdated(measureAll)
</script>
19 changes: 10 additions & 9 deletions examples/vue/dynamic/src/components/RowVirtualizerDynamic.vue
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Original file line number Diff line number Diff line change
Expand Up @@ -35,7 +35,7 @@
v-for="virtualRow in virtualRows"
:key="virtualRow.key"
:data-index="virtualRow.index"
:ref="measureElement"
ref="virtualItemEls"
:class="virtualRow.index % 2 ? 'ListItemOdd' : 'ListItemEven'"
>
<div style="padding: 10px 0">
Expand All @@ -50,7 +50,7 @@
</template>

<script setup lang="ts">
import { ref, computed } from 'vue'
import { computed, onMounted, onUpdated, ref, shallowRef } from 'vue'
import { useVirtualizer } from '@tanstack/vue-virtual'
import { generateSentences } from './utils'

Expand All @@ -68,13 +68,14 @@ const virtualRows = computed(() => rowVirtualizer.value.getVirtualItems())

const totalSize = computed(() => rowVirtualizer.value.getTotalSize())

const measureElement = (el) => {
if (!el) {
return
}
const virtualItemEls = shallowRef([])
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shallowRef([]) with an empty array literal infers never[] in TypeScript, which can make el in forEach be never and cause type errors when passing it to measureElement. Consider explicitly typing virtualItemEls (e.g. as an array of HTMLElement | null).

Suggested change
const virtualItemEls = shallowRef([])
const virtualItemEls = shallowRef<(HTMLElement | null)[]>([])

Copilot uses AI. Check for mistakes.

rowVirtualizer.value.measureElement(el)

return undefined
function measureAll() {
virtualItemEls.value.forEach((el) => {
if (el) rowVirtualizer.value.measureElement(el)
})
}
Comment on lines +73 to 77
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measureAll never calls rowVirtualizer.value.measureElement(null). In @tanstack/virtual-core, passing null is what triggers cleanup of disconnected nodes (unobserving/removing stale entries from elementsCache). Without that, items that scroll out/unmount can remain observed/retained. Consider calling measureElement(null) once per update (or using a callback ref that forwards null on unmount) in addition to measuring the current elements.

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onMounted(measureAll)
onUpdated(measureAll)
Comment on lines +79 to +80
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onUpdated(measureAll) runs after every component update, including scroll-driven updates as virtualRows changes. Measuring all rendered items on every update can be expensive (forces layout reads) and may reintroduce scroll jank. Consider a more targeted trigger (e.g. defer measurement from an element ref callback post-render, or only measure newly mounted items) to avoid repeated full measurement passes.

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</script>
19 changes: 10 additions & 9 deletions examples/vue/dynamic/src/components/RowVirtualizerDynamicWindow.vue
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Original file line number Diff line number Diff line change
Expand Up @@ -22,7 +22,7 @@
v-for="virtualRow in virtualRows"
:key="virtualRow.key"
:data-index="virtualRow.index"
:ref="measureElement"
ref="virtualItemEls"
:class="virtualRow.index % 2 ? 'ListItemOdd' : 'ListItemEven'"
>
<div style="padding: 10px 0">
Expand All @@ -36,7 +36,7 @@
</template>

<script setup lang="ts">
import { ref, computed, onMounted } from 'vue'
import { computed, onMounted, onUpdated, ref, shallowRef } from 'vue'
import { useWindowVirtualizer } from '@tanstack/vue-virtual'
import { generateSentences } from './utils'

Expand Down Expand Up @@ -64,13 +64,14 @@ const virtualRows = computed(() => rowVirtualizer.value.getVirtualItems())

const totalSize = computed(() => rowVirtualizer.value.getTotalSize())

const measureElement = (el) => {
if (!el) {
return
}

rowVirtualizer.value.measureElement(el)
const virtualItemEls = shallowRef([])
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Copilot AI Mar 12, 2026

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shallowRef([]) with an empty array literal infers never[] in TypeScript, which can make el in forEach be never and cause type errors when passing it to measureElement. Consider explicitly typing virtualItemEls (e.g. as an array of HTMLElement | null).

Suggested change
const virtualItemEls = shallowRef([])
const virtualItemEls = shallowRef<(HTMLElement | null)[]>([])

Copilot uses AI. Check for mistakes.

return undefined
function measureAll() {
virtualItemEls.value.forEach((el) => {
if (el) rowVirtualizer.value.measureElement(el)
})
}
Comment on lines +69 to 73
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Copilot AI Mar 12, 2026

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measureAll never calls rowVirtualizer.value.measureElement(null). In @tanstack/virtual-core, passing null is what triggers cleanup of disconnected nodes (unobserving/removing stale entries from elementsCache). Without that, items that scroll out/unmount can remain observed/retained. Consider calling measureElement(null) once per update (or using a callback ref that forwards null on unmount) in addition to measuring the current elements.

Copilot uses AI. Check for mistakes.

onMounted(measureAll)
onUpdated(measureAll)
Comment on lines +75 to +76
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Copilot AI Mar 12, 2026

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onUpdated(measureAll) runs after every component update, including scroll-driven updates as virtualRows changes. Measuring all rendered items on every update can be expensive (forces layout reads) and may reintroduce scroll jank. Consider a more targeted trigger (e.g. defer measurement from an element ref callback post-render, or only measure newly mounted items) to avoid repeated full measurement passes.

Copilot uses AI. Check for mistakes.
</script>
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