agent-skills/skills/vueuse-functions/references/useVirtualList.md

category

category
Component

useVirtualList

::: warning Consider using vue-virtual-scroller instead, if you are looking for more features. :::

Create virtual lists with ease. Virtual lists (sometimes called virtual scrollers) allow you to render a large number of items performantly. They only render the minimum number of DOM nodes necessary to show the items within the container element by using the wrapper element to emulate the container element's full height.

Usage

Simple list

import { useVirtualList } from '@vueuse/core'

const { list, containerProps, wrapperProps } = useVirtualList(
  Array.from(Array.from({ length: 99999 }).keys()),
  {
    // Keep `itemHeight` in sync with the item's row.
    itemHeight: 22,
  },
)

Config

State	Type	Description
itemHeight	number	ensure that the total height of the wrapper element is calculated correctly.*
itemWidth	number	ensure that the total width of the wrapper element is calculated correctly.*
overscan	number	number of pre-rendered DOM nodes. Prevents whitespace between items if you scroll very quickly.

* The itemHeight or itemWidth must be kept in sync with the height of each row rendered. If you are seeing extra whitespace or jitter when scrolling to the bottom of the list, ensure the itemHeight or itemWidth is the same height as the row.

Reactive list

import { useToggle, useVirtualList } from '@vueuse/core'
import { computed } from 'vue'

const [isEven, toggle] = useToggle()
const allItems = Array.from(Array.from({ length: 99999 }).keys())
const filteredList = computed(() => allItems.filter(i => isEven.value ? i % 2 === 0 : i % 2 === 1))

const { list, containerProps, wrapperProps } = useVirtualList(
  filteredList,
  {
    itemHeight: 22,
  },
)

<template>
  <p>Showing {{ isEven ? 'even' : 'odd' }} items</p>
  <button @click="toggle">
    Toggle Even/Odd
  </button>
  <div v-bind="containerProps" style="height: 300px">
    <div v-bind="wrapperProps">
      <div v-for="item in list" :key="item.index" style="height: 22px">
        Row: {{ item.data }}
      </div>
    </div>
  </div>
</template>

Horizontal list

import { useVirtualList } from '@vueuse/core'

const allItems = Array.from(Array.from({ length: 99999 }).keys())

const { list, containerProps, wrapperProps } = useVirtualList(
  allItems,
  {
    itemWidth: 200,
  },
)

<template>
  <div v-bind="containerProps" style="height: 300px">
    <div v-bind="wrapperProps">
      <div v-for="item in list" :key="item.index" style="width: 200px">
        Row: {{ item.data }}
      </div>
    </div>
  </div>
</template>

Component Usage

<template>
  <UseVirtualList :list="list" :options="options" height="300px">
    <template #default="props">
      <!-- you can get current item of list here -->
      <div style="height: 22px">
        Row {{ props.index }} {{ props.data }}
      </div>
    </template>
  </UseVirtualList>
</template>

To scroll to a specific element, the component exposes scrollTo(index: number) => void.

Type Declarations

type UseVirtualListItemSize = number | ((index: number) => number)
export interface UseHorizontalVirtualListOptions
  extends UseVirtualListOptionsBase {
  /**
   * item width, accept a pixel value or a function that returns the width
   *
   * @default 0
   */
  itemWidth: UseVirtualListItemSize
}
export interface UseVerticalVirtualListOptions
  extends UseVirtualListOptionsBase {
  /**
   * item height, accept a pixel value or a function that returns the height
   *
   * @default 0
   */
  itemHeight: UseVirtualListItemSize
}
export interface UseVirtualListOptionsBase {
  /**
   * the extra buffer items outside of the view area
   *
   * @default 5
   */
  overscan?: number
}
export type UseVirtualListOptions =
  | UseHorizontalVirtualListOptions
  | UseVerticalVirtualListOptions
export interface UseVirtualListItem<T> {
  data: T
  index: number
}
export interface UseVirtualListReturn<T> {
  list: Ref<UseVirtualListItem<T>[]>
  scrollTo: (index: number) => void
  containerProps: {
    ref: Ref<HTMLElement | null>
    onScroll: () => void
    style: StyleValue
  }
  wrapperProps: ComputedRef<{
    style:
      | {
          width: string
          height: string
          marginTop: string
        }
      | {
          width: string
          height: string
          marginLeft: string
          display: string
        }
  }>
}
/**
 * Please consider using [`vue-virtual-scroller`](https://github.com/Akryum/vue-virtual-scroller) if you are looking for more features.
 */
export declare function useVirtualList<T = any>(
  list: MaybeRef<readonly T[]>,
  options: UseVirtualListOptions,
): UseVirtualListReturn<T>