Plugins
addExpandedRows
addExpandedRows expands and collapses sub-rows of rows. Sub-rows are defined by plugins such as 
addSubRows or 
addGroupBy.
Options
Options passed into addExpandedRows.
const table = createTable(data, {
  expand: addExpandedRows({ ... }),
});
 initialExpandedIds?: Record<string, boolean>
Sets the initial expanded row ids.
Expanded row ids are stored as an object of row ids to booleans. If expandedIds[rowId] is true, then rowId is expanded. Otherwise, rowId is not expanded.
The id of a sub-row is in the format {parentId}>{id}. A nested sub-row can be referred to by concatenating the ids of its parent rows to the top-level row.
Defaults to {}.
Column Options
Options passed into column definitions.
const columns = table.createColumns([
  table.column({
    header: 'Name',
    accessor: 'name',
    plugins: {
      expand: { ... },
    },
  }),
]);
Nothing here so far.
Prop Set
Extensions to the view model.
Subscribe to .props() on the respective table components.
{#each $headerRows as headerRow (headerRow.id)}
  <Subscribe rowProps={headerRow.props()} let:rowProps>
    {rowProps.expand} <!-- HeaderRow props -->
    {#each headerRow.cells as cell (cell.id)}
      <Subscribe props={cell.props()} let:props>
        {props.expand} <!-- HeaderCell props -->
      </Subscribe>
    {/each}
  </Subscribe>
{/each}
Nothing here so far.
Plugin State
State provided by addExpandedRows.
const { headerRows, rows, pluginStates } = table.createViewModel(columns);
const { ... } = pluginStates.expand;
 expandedIds: Writable<Record<string, boolean>>
The current expanded row ids. Expanded row ids are stored as an object of row ids to booleans. If expandedIds[rowId] is true, then rowId is expanded. If expandedIds[rowId] is undefined or false, then rowId is not expanded.
The id of a sub-row is in the format {parentId}>{id}. A nested sub-row can be referred to by concatenating the ids of its parent rows to the top-level row.
 getRowState: (row) => ExpandedRowsRowState
getRowState takes a BodyRow and returns ExpandedRowsRowState for the row.
 ExpandedRowsRowState#isExpanded: Writable<boolean>
Whether the row is expanded. Update the store to update the expanded state of the row.
 ExpandedRowsRowState#canExpand: Readable<boolean>
Whether the row has sub-rows to expand.
 ExpandedRowsRowState#isAllSubRowsExpanded: Readable<boolean>
Whether all sub-rows of the row are also expanded. If sub-rows are not expandable, defaults to true.