Data Grid

<loomi-data-grid> — a modular data grid. The core is deliberately lean (rendering, sorting, pagination, selection, column resizing, sticky headers, keyboard navigation, and custom cell rendering); everything else — filtering, row grouping, tree data, export, inline editing, virtual scrolling, pivot tables, charts integration, spreadsheet features, and state persistence — is an opt-in module you attach only when you need it.

Accessibility

• Roving cell focus: Arrow keys, Home/End, Page Up/Down; Space toggles row selection; Enter fires loomi-row-action.
• Module toolbars expose labelled controls (aria-label on filters and actions).

For the library-wide baseline, see Foundations — Accessibility.

Responsive behavior

• Toolbar and footer groups stack below 768px.

For the shared container and viewport rules, see Foundations — Responsive behavior.

Dark mode

For theme activation, token overrides, and contrast guidance, see Foundations — Dark mode.

Installation

npm install @loomidev/data-grid lit

Import

import "@loomidev/data-grid";

Core usage

Set columns and data as JavaScript properties.

const grid = document.querySelector("loomi-data-grid");

grid.columns = [
  { key: "name", label: "Name", sortable: true, resizable: true },
  { key: "email", label: "Email" },
  { key: "role", label: "Role" },
  {
    key: "status",
    label: "Status",
    cellRenderer: ({ value }) => html`<loomi-tag color=${value === "Active" ? "green" : "gray"}>${value}</loomi-tag>`
  }
];

grid.data = [
  { id: "usr_001", name: "Emma Miller", email: "emma@example.com", role: "Owner", status: "Active" },
  { id: "usr_002", name: "Diego Barros", email: "diego@example.com", role: "Admin", status: "Invited" }
];

<loomi-data-grid selectable sticky-header max-height="480px"></loomi-data-grid>

Core features

• Rendering — pass columns + data; each column supports formatter (string) or cellRenderer (full lit template) for custom cell content.
• Sorting — set column.sortable; click a header to cycle asc → desc → none. Listen for loomi-sort-change.
• Pagination — pagination, page, page-size, total-rows (for server-side mode). Listen for loomi-page-change.
• Selection — selectable renders checkboxes; selectedKeys is a JavaScript property. Space bar toggles the focused row. Listen for loomi-selection-change.
• Column resizing — drag the handle at a header’s right edge (disable per-column with resizable: false). Listen for loomi-column-resize. Widths land in grid.columnWidths.
• Column pinning — set column.pinned to "start" or "end" to keep columns visible while scrolling horizontally. When selectable is on, the checkbox column is pinned to the start automatically.
• Sticky headers — sticky-header (default on) plus max-height on the grid for a real scroll container.
• Keyboard navigation — arrow keys move a roving cell focus, Home/End jump to the row’s first/last column, PageUp/PageDown change page, Enter fires loomi-row-action, Space toggles selection.
• Custom cell rendering — column.cellRenderer(ctx) returns anything lit-html can render (templates, elements, strings).

Server-side mode

<loomi-data-grid server-side total-rows="482" sticky-header></loomi-data-grid>

In server-side mode the grid renders data as-is — no local filter, sort, or pagination — you own fetching. Listen for loomi-page-change and loomi-sort-change to refetch.

Modules

Modules are plain factory functions you assign to grid.modules. Each module only implements the hooks it needs (see GridModule in grid-module.ts), so composing several is just concatenating arrays. Import each one from its own entry point — the package root does not re-export modules — so bundlers only pull in what you use:

import "@loomidev/data-grid";
import { filteringModule } from "@loomidev/data-grid/modules/filtering.js";
import { exportModule } from "@loomidev/data-grid/modules/export.js";

grid.modules = [filteringModule({ searchPlaceholder: "Search users" }), exportModule({ filename: "users" })];

Filtering (modules/filtering.js)

Global quick-search box plus a per-column filter input for columns with filterable: true.

import { filteringModule } from "@loomidev/data-grid/modules/filtering.js";
grid.modules = [filteringModule()];

Row grouping (modules/row-grouping.js)

Groups rows by a column into collapsible sections with per-column aggregates.

import { rowGroupingModule } from "@loomidev/data-grid/modules/row-grouping.js";
grid.modules = [rowGroupingModule({ groupBy: "department", aggregates: { salary: "avg" } })];

Tree data (modules/tree-data.js)

Flattens hierarchical rows (nodes with a children array) into an indented, expand/collapsible list.

import { treeDataModule } from "@loomidev/data-grid/modules/tree-data.js";
grid.data = [{ id: "1", name: "Engineering", children: [{ id: "1a", name: "Platform" }] }];
grid.modules = [treeDataModule()];

Export (modules/export.js)

Adds CSV/JSON export buttons to the toolbar and dispatches loomi-export-request (rows + columns) so you can hook in server-side exports (Excel, PDF) too.

import { exportModule } from "@loomidev/data-grid/modules/export.js";
grid.modules = [exportModule({ filename: "members", formats: ["csv", "json"] })];

Inline editing (modules/inline-editing.js)

Double-click (or press Enter on) a cell whose column is editable: true to edit it; commit with Enter/blur, cancel with Escape. Edits flow through grid.updateCellValue(...) and emit loomi-cell-edit.

import { inlineEditingModule } from "@loomidev/data-grid/modules/inline-editing.js";
grid.columns = [{ key: "name", label: "Name", editable: true }];
grid.modules = [inlineEditingModule()];

Virtual scrolling (modules/virtual-scrolling.js)

Renders only the rows visible in the scroll viewport for large datasets. Set max-height so the grid actually scrolls, and turn off pagination.

import { virtualScrollingModule } from "@loomidev/data-grid/modules/virtual-scrolling.js";
grid.maxHeight = "480px";
grid.pagination = false;
grid.modules = [virtualScrollingModule({ rowHeight: 40 })];

Pivot tables (modules/pivot.js)

Reshapes flat rows into a row/column/value pivot matrix.

import { pivotModule } from "@loomidev/data-grid/modules/pivot.js";
grid.modules = [pivotModule({ rowField: "region", columnField: "quarter", valueField: "revenue", aggregate: "sum" })];

Charts integration (modules/charts.js)

Renders a <loomi-chart> below the grid summarizing the current rows. Pulls in @loomidev/chart.

import { chartsModule } from "@loomidev/data-grid/modules/charts.js";
grid.modules = [chartsModule({ labelField: "month", valueField: "revenue", type: "line" })];

Spreadsheet features (modules/spreadsheet.js)

Click-drag or shift+arrow to select a rectangular cell range, Ctrl/Cmd+C to copy as TSV, Ctrl/Cmd+V to paste back in starting at the anchor cell.

import { spreadsheetModule } from "@loomidev/data-grid/modules/spreadsheet.js";
grid.modules = [spreadsheetModule()];

State persistence (modules/state-persistence.js)

Saves sort, column widths, page, and page size to localStorage (or sessionStorage), restoring them next time a grid with the same key attaches.

import { statePersistenceModule } from "@loomidev/data-grid/modules/state-persistence.js";
grid.modules = [statePersistenceModule({ key: "members-grid" })];

Saved views (modules/saved-views.js)

Renders a view picker in the toolbar and applies named presets for sort, page size, column visibility, column widths, and filters. Register filteringModule() before savedViewsModule() so filter presets flow through the filtering module’s setFilterState() API.

import { filteringModule } from "@loomidev/data-grid/modules/filtering.js";
import { savedViewsModule } from "@loomidev/data-grid/modules/saved-views.js";

grid.modules = [
  filteringModule(),
  savedViewsModule({
    views: [
      {
        id: "active",
        label: "Active users",
        filters: [{ key: "status", value: "Active" }],
        pageSize: 25,
        sort: { key: "name", direction: "asc" },
      },
    ],
    activeViewId: "active",
  }),
];

Listen for loomi-saved-view-change when the user switches views. To update views at runtime, dispatch loomi-saved-view-config with { views, activeViewId }.

Combining modules

Modules compose by array order. transformRows hooks run in two stages — "filter" (before core sorting: filtering) then "shape" (after sorting: row grouping, tree data, pivot) — so, for example, filtering + sorting + grouping + export all work together:

grid.modules = [
  filteringModule(),
  rowGroupingModule({ groupBy: "department" }),
  exportModule({ filename: "team" }),
  statePersistenceModule({ key: "team-grid" })
];

Writing your own module

A module is any object matching the GridModule interface — implement only the hooks you need:

import { defineGridModule } from "@loomidev/data-grid";

export function highlightNegativesModule(columnKey: string) {
  return defineGridModule({
    name: "highlight-negatives",
    getCellClass(cell) {
      return cell.column.key === columnKey && Number(cell.row[columnKey]) < 0 ? "negative" : undefined;
    }
  });
}

See grid-module.ts for the full hook list: transformRows, transformColumns, renderToolbarStart/renderToolbarEnd, renderHeaderExtra, renderBelowTable, renderBody, renderCell, getRowClass/getCellClass, onCellKeydown, onCellPointerDown/ onCellPointerEnter, onCellDblClick, and onGridEvent.

React usage

React apps should use @loomidev/react (planned) once the wrapper for this component is implemented. The wrapper should pass arrays/objects as DOM properties and map custom events to callbacks — it should not reimplement grid rendering or behavior.

Events

Event	Detail
loomi-page-change	{ page, pageSize }
loomi-sort-change	{ sort }
loomi-selection-change	{ selectedKeys, selectedRows }
loomi-row-action	{ row, rowKey }
loomi-column-resize	{ key, width }
loomi-cell-edit	{ row, rowKey, columnKey, previousValue, value }
loomi-grid-toggle-row	{ rowKey, row, expanded } (row grouping / tree data)
loomi-export-request	{ format, rows, columns, selectedOnly } (export module)
loomi-saved-view-change	{ viewId, view } (saved views module)

Design notes

• row-key defaults to id.
• data and columns are JavaScript properties, not string attributes.
• Rows produced by a module (group headers, pivot summaries) carry a reserved __gridMeta field — don’t use that key in your own records.
• formatter/cellRenderer belong on column definitions for app-specific display logic; use modules for cross-cutting behavior.
• Inline editing and spreadsheet paste both write through grid.updateCellValue(rowKey, columnKey, value), which operates on top-level data rows — combining them with row grouping or tree data needs care since those modules render synthetic/cloned rows.

Migrating from @loomidev/data-table

@loomidev/data-table (<loomi-data-table>) has been replaced by this package. Changes to account for:

• Tag: <loomi-data-table> → <loomi-data-grid>.
• Package: @loomidev/data-table → @loomidev/data-grid.
• Global search, per-column filters, and export are no longer built in — use filteringModule() and exportModule().
• Saved views are provided by savedViewsModule() (register after filteringModule() when a preset includes filters).
• A column-visibility manager is not yet reimplemented as a module.
• Types are renamed DataTable* → DataGrid*, and filter-related types (DataGridFilter, DataGridFilterOperator) now live in modules/filtering.js.

Dependencies

• @loomidev/chart
• @loomidev/core