XLSX

Library for rendering JSON Table trees to XLSX workbooks.

Installation

npm

npm i @json-table/core @json-table/xlsx

yarn

yarn add @json-table/core @json-table/xlsx

pnpm

pnpm add @json-table/core @json-table/xlsx

bun

bun add @json-table/core @json-table/xlsx

@office-kit/xlsx is a peer dependency and is installed automatically as such.

Usage

import { makeTreeFactory } from "@json-table/core";
import { treesToWorkbook, treesToXlsxBytes } from "@json-table/xlsx";

const createTree = makeTreeFactory({
  cornerCellValue: "№",
  createHeader: (key) => key,
  createIndex: (i) => i + 1,
});

const tree = createTree(data);

/* Create a workbook with a `Table` sheet */
const wb = treesToWorkbook([["Table", tree]]);

/* Or serialize directly to bytes (browser-safe) */
const bytes = await treesToXlsxBytes([["Table", tree]]);

Every cell of the tree is placed on the worksheet with rowspan/colspan-equivalent merges; header, index and corner cells are rendered in bold (centered, wrapped).

Lower-level helpers are also exported:

• renderOnWorksheet(ws, wb, tree, options) — render one tree onto an existing worksheet.
• calculateSheetData(tree, options) — compute { widths, heights, cells } without writing anything.

Sizing

Column widths and row heights are computed with a two-pass autofit algorithm:

1. Widths — per column, the p90 of content lengths of the single-row cells occupying it plus one character to compensate for Excel’s internal cell padding (so a single huge value wraps instead of widening the column), floored at cellMinWidth.
2. Heights — estimated wrapped-line counts using pass-1 widths as wrap capacity, spread across merged rows and multiplied by the line height, floored at cellMinHeight.

Both floors can be customized through options (cellMinWidth, default 10, in Excel character units; cellMinHeight, default 15, in points):

import { treesToXlsxBytes } from "@json-table/xlsx";

const bytes = await treesToXlsxBytes([["Table", tree]], {
  cellMinWidth: 8,
  cellMinHeight: 20,
});

License

MIT