--- title: Virtualized Table lang: en-US --- # Virtualized Table Along with the evolutionary web development, table component has always been the most popular component in our web apps especially for dashboards, data analysis. For [Table V1](./table.md), with even just 1000 records of data, it can be very annoying when using it, because the poor performance. With Virtualized Table, you can render massive chunks of data in a blink of an eye. :::tip This component is **still under testing**, use at your own risk. if you found any bug or issue please report it at [GitHub](https://github.com/element-plus/element-plus/issues) for us to fix. Also there were some APIs which was not mentioned in this documentation, some of them were not fully developed yet, so that we are not mentioning them here. **Even though** Virtualized Table is efficient, but when the data load is too big, your **network**, **memory size** can be the bottle neck of your app. So keep in mind that Virtualized Table is never the ultimate solution for everything, consider paginate your data, add filters etc. ::: ## Basic usage Let's render a basic case of Virtualized Table with 10 columns by 1000 rows, to demonstrate how performant it is. :::demo table-v2/basic ::: ## Customize Cell Renderer Of course, you can render the table cell per your needs, here is a simple example of how to customize your cell. :::demo table-v2/cell-templating ::: ## Table with status You can highlight your table content to distinguish between "success, information, warning, danger" and other states. Use `row-class-name` to customize how the row looks. In this case, every 10th row will be highlighted with `bg-blue-200` class, every 5th row will be highlighted with `bg-red-100` class. :::demo table-v2/row-class ::: ## Table with sticky rows You can make some rows stick to the top of the table, and that can be very easily achieved by using `fixed-data` attribute. You can add dynamically set the sticky row with scroll events like this example did. :::demo table-v2/sticky-rows ::: ## Table with fixed columns For some reason, you want to make the columns stick on the left and right, you can do that by adding special attributes for table. You can set the column's attribute `fixed` to `true` (representing `FixedDir.LEFT`) or `FixedDir.LEFT` or `FixedDir.RIGHT` :::demo table-v2/fixed-columns ::: ## Grouping header By customizing your header renderer you can group your header like this example did. :::tip In this case we used `JSX` feature which is not supported in the playground, you may try them out in your local environment or online IDEs such as `codesandbox`. It is recommended that you write your table component in JSX, since it contains VNode manipulations. ::: :::demo table-v2/grouping-header ::: ## Filter Virtualized Table providers customizing header renderers for rendering customized header, then we can use that to render filters :::demo table-v2/filter ::: ## Sortable You can sort the table with sort state. :::demo table-v2/sort ::: ## Controlled Sort You can define multiple sortable column when you need it. Keep in mind that if you define multiple sortable columns, the UI might seem strange to your users since the it is unclear which column is being sorted. :::demo table-v2/controlled-sort ::: ## Colspan Virtualized table did not use built-in `table` element, so that `colspan` and `rowspan` is a little bit different than [TableV1](./table.md). With customized row renderer, we can still do that. In this case, you'll learn how to do that. :::demo table-v2/colspan ::: ## Rowspan Since we have [Colspan](#colspan) of course we have row span as well, it is a little bit different than colspan but the idea is basically the same. :::demo table-v2/rowspan ::: ## Rowspan and Colspan together We can combine rowspan and colspan together to meet your business goal! :::demo table-v2/spans ::: ## Tree data Virtual Table can also render data like tree, you can expand/collapse the tree node by clicking the arrow icon. :::demo table-v2/tree-data ::: ## Dynamic height rows Virtual Table can also render rows with dynamic height, when you have data without knowing how big the content it would be, you might want to use this feature for rendering a dynamic height row. You must pass down `estimated-row-height` to enable this feature, and the closer the estimated height is, the smoother the rendering will be. :::tip The height of each row is dynamically measured while rendering the rows, so that the UI **might be** bouncing if you are trying to render a large amount of data. ::: :::demo table-v2/dynamic-height ::: ## Detail view With dynamic height rendering, we can use that to render detail view in the table. :::demo table-v2/detailed-view ::: ## Customized Footer Rendering a customized footer when you want to show a concluding message or information. :::demo table-v2/footer ::: ## Customized Empty Renderer Render customized empty element :::demo table-v2/empty ::: ## Overlay Render an overlay above the table when you want to show a loading indicator or something else. :::demo table-v2/overlay ::: ## TableV2 Attributes | Attribute | Description | Type | Default | | ------------------------- | -------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------- | --------- | | cache | Number of rows rendered in advance for boosting the performance | Number | 2 | | estimated-row-height | The estimated row height for rendering dynamic height rows | Number | - | | header-class | Customized class name passed to header wrapper | String/Function\<[HeaderClassGetter](#typings)\> | - | | header-props | Customized props name passed to header component | Object/Function\<[HeaderPropsGetter](#typings)\> | - | | header-cell-props | Customized props name passed to header cell component | Object/Function\<[HeaderCellPropsGetter](#typings)\> | - | | header-height | The height of entire header, when it's array, it will render as many header rows as the given array's length | Number/Array\ | 50 | | footer-height | The height of the footer element, when presented, it will be part of the calculation of the table's height. | Number | 0 | | row-class | Customized class name passed to row wrapper | String/Function\<[RowClassGetter](#typings)\> | - | | row-key | The key of each row, if not provided, it will be the index of the row | String/Symbol/Number | id | | row-props | Customized props name passed to row component | Object/Function\<[RowPropsGetter](#typings)\> | - | | row-height | The height of each row, used for calculating the total height of the table | Number | 50 | | columns | An array of column definitions. | Array\<[Column](#column-attribute)\> | - | | data | An array of data to be rendered in the table. | Array\<[Data](#typings)\> | [] | | data-getter | An method which helps customizing the how to fetch the data from the data source. | Function | - | | fixed-data | Data for rendering rows above the main content and below the header | Array\<[Data](#typings)\> | - | | expand-column-key | The column key indicates which row is expandable | String | - | | expanded-row-keys | An array of keys for expanded rows, can be used with `v-model` | Array\<[KeyType](#typings)\> | - | | default-expanded-row-keys | An array of keys for default expanded rows, **NON REACTIVE** | Array\<[KeyType](#typings)\> | - | | class | Class name for the the virtual table, will be applied to all three tables (left, right, main) | String/Array/Object | - | | fixed | Flag indicates the table column's width is a fixed or flexible. | Boolean | false | | width \* | Width for the table, required | Number | - | | height \* | Height for the table, required | Number | - | | max-height | Maximum height for the table | Number | - | | h-scrollbar-size | Indicates the horizontal scrollbar's size for the table, used to prevent the horizontal and vertical scrollbar to collapse | Number | 6 | | v-scrollbar-size | Indicates the horizontal scrollbar's size for the table, used to prevent the horizontal and vertical scrollbar to collapse | Number | 6 | | scrollbar-always-on | If true, the scrollbar will always be shown instead of when mouse is placed above the table | Boolean | false | | sort-by | Sort indicator | Object\<[SortBy](#typings)\> | {} | | sort-state | Multiple sort indicator | Object\<[SortState](#typings)\> | undefined | ## TableV2 Slots | Name | Params | | ----------- | ------------------------------- | | cell | [CellSlotProps](#typings) | | header | [HeaderSlotProps](#typings) | | header-cell | [HeaderCellSlotProps](#typings) | | row | [RowSlotProps](#typings) | | footer | - | | empty | - | | overlay | - | ## Table Methods | Event Name | Description | Parameters | | -------------------- | --------------------------------------------- | ---------------------------------------- | | column-sort | Invoked when column sorted | Object\ | | expanded-rows-change | Invoked when expanded rows changed | `Array` | | end-reached | Invoked when the end of the table is reached | - | | scroll | Invoked after scrolled | Object\<[ScrollParams](#typings)\> | | rows-rendered | Invoked when rows are rendered | Object\<[RowsRenderedParams](#typings)\> | | row-event-handlers | A collection of handlers attached to each row | Object\<[RowEventHandlers](#typings)\> | :::tip Note that these are `JavaScript` Objects, so that you **CANNOT USE** kebab-case for these attributes ::: ## Column Attribute | Attribute | Description | Type | Default | | -------------- | ------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------- | | align | Alignment of the table cell content | [Alignment](https://github.com/element-plus/element-plus/blob/b92b22932758f0ddea98810ae248f6ca62f77e25/packages/components/table-v2/src/constants.ts#L6) | left | | class | Class name for the column | String | - | | fixed | Fixed direction of the column | Boolean/[FixedDir](https://github.com/element-plus/element-plus/blob/b92b22932758f0ddea98810ae248f6ca62f77e25/packages/components/table-v2/src/constants.ts#L11) | false | | flexGrow | CSSProperties flex grow, Only useful when not this is not a fixed table | Number | 0 | | flexShrink | CSSProperties flex shrink, Only useful when not this is not a fixed table | Number | 1 | | headerClass | Used for customizing header column class | String | - | | hidden | Whether the column is invisible | Boolean | - | | style | Customized style for column cell, will be merged with grid cell | CSSProperties | - | | sortable | Indicates whether the column is sortable | Boolean | - | | title | The default text rendered in header cell | String | - | | maxWidth | Maximum width for the column | String | - | | minWidth | Minimum width for the column | String | - | | width \* | Width for the column **Required** | Number | - | | cellRenderer | Customized Cell renderer | VueComponent/(props: [CellRenderProps](#renderer-typings)) => VNode | - | | headerRenderer | Customized Header renderer | VueComponent/(props: [HeaderRenderProps](#renderer-typings)) => VNode | - | ## Typings
Show Type Declarations ```ts type HeaderClassGetter = (param: { columns: Column[] headerIndex: number }) => string type HeaderPropsGetter = (param: { columns: Column[] headerIndex: number }) => Record type HeaderCellPropsGetter = (param: { columns: Column[] column: Column columnIndex: number headerIndex: number style: CSSProperties }) => Record type RowClassGetter = (param: { columns: Column[] rowData: any rowIndex: number }) => string type RowPropsGetter = (param: { columns: Column[] rowData: any rowIndex: number }) => Record type CellRenderProps = { cellData: T column: Column columns: Column[] columnIndex: number rowData: any rowIndex: number } type HeaderRenderProps = { column: Column columns: Column[] columnIndex: number headerIndex: number } type ScrollParams = { xAxisScrollDir: 'forward' | 'backward' scrollLeft: number yAxisScrollDir: 'forward' | 'backward' scrollTop: number } type CellSlotProps = { column: Column columns: Column[] columnIndex: number depth: number style: CSSProperties rowData: any rowIndex: number isScrolling: boolean expandIconProps?: | { rowData: any rowIndex: number onExpand: (expand: boolean) => void } | undefined } type HeaderSlotProps = { cells: VNode[] columns: Column[] headerIndex: number } type HeaderCellSlotProps = { class: string columns: Column[] column: Column columnIndex: number headerIndex: number style: CSSProperties headerCellProps?: any sortBy: SortBy sortState?: SortState | undefined onColumnSorted: (e: MouseEvent) => void } type RowSlotProps = { columnIndex: number rowIndex: number data: any key: number | string isScrolling?: boolean | undefined style: CSSProperties } type Data = { [key: KeyType]: any children?: Array } type FixedData = Data type KeyType = string | number | symbol type ColumnSortParam = { column: Column; key: KeyType; order: SortOrder } enum SortOrder { ASC = 'asc', DESC = 'desc', } type SortBy = { key: KeyType; Order: SortOrder } type SortState = Record ```