exceljs-formula-recalc

Recalculate formulas in an ExcelJS workbook without opening Excel, LibreOffice, or a browser.

ExcelJS can read and write formula cells, but it does not run an Excel-compatible calculation engine for you after backend code edits inputs. This package bridges that gap: serialize the ExcelJS workbook, run the Bilig WorkPaper recalculation path, optionally load the recalculated XLSX back into the same ExcelJS workbook, and read proof values.

If You Arrived From an ExcelJS Formula Issue

This package is for the recurring ExcelJS boundary behind issues and searches like:

• ExcelJS formula result not updating
• Formula based cell not updating
• Updating Formula Result
• Automatic formula calculation
• get computed value of Excel sheet cell in Node.js

The important distinction is:

• workbook.calcProperties.fullCalcOnLoad = true asks Excel or LibreOffice to recalculate later, when the file is opened.
• exceljs-formula-recalc recalculates before your Node process returns, then patches requested ExcelJS formula cells with fresh result values.

Use ExcelJS for workbook I/O and presentation. Use this package only for the calculation/readback boundary that ExcelJS intentionally does not own.

For a cross-library proof, run examples/recalc-bridge-workflows. It edits the same workbook through SheetJS/xlsx, xlsx-populate, and ExcelJS, then verifies that Bilig refreshes the stale formula result.

Install

npm install exceljs exceljs-formula-recalc

CLI

If your ExcelJS workflow has already written an .xlsx file, the package also ships an ExcelJS-named CLI for quick proof runs:

npx --package exceljs-formula-recalc exceljs-recalc --demo --json

For a real workbook saved by ExcelJS:

npx --package exceljs-formula-recalc exceljs-recalc quote.xlsx \
  --set Inputs!B2=48 \
  --set Inputs!B3=1500 \
  --read Summary!B7 \
  --out quote.recalculated.xlsx \
  --json

Use the API below when backend code needs the recalculated values patched back onto the in-memory ExcelJS workbook object.

Use With ExcelJS

import ExcelJS from 'exceljs'
import { recalculateExceljsWorkbook } from 'exceljs-formula-recalc'

const workbook = new ExcelJS.Workbook()
await workbook.xlsx.readFile('quote.xlsx')

const result = await recalculateExceljsWorkbook(workbook, {
  edits: [
    { target: 'Inputs!B2', value: 48 },
    { target: 'Inputs!B3', value: 1500 },
  ],
  reads: ['Summary!B7'],
})

console.log(result.reads['Summary!B7'])
await workbook.xlsx.writeFile('quote.recalculated.xlsx')

By default, recalculateExceljsWorkbook mutates the provided ExcelJS workbook by loading the recalculated XLSX bytes back into it. For targets listed in reads, it also patches the ExcelJS formula cell object with the recalculated result, so backend code can inspect proof values without reopening the file. Pass mutateWorkbook: false if you only need the returned xlsx bytes.

Common Boundaries

| Job | Use | | --------------------------------------------------------------- | -------------------------------------- | | Create styled XLSX reports, worksheets, tables, images, or rows | ExcelJS | | Ask Excel to recalculate after a human opens the file | ExcelJS fullCalcOnLoad | | Read recalculated formula values before an API/job returns | exceljs-formula-recalc | | Recalculate raw XLSX bytes from SheetJS or xlsx-populate | xlsx-formula-recalc | | Keep formula-backed business state as JSON, not XLSX | @bilig/headless or bilig-workpaper |

API

import { recalculateExceljsBuffer, recalculateExceljsWorkbook } from 'exceljs-formula-recalc'

recalculateExceljsWorkbook(workbook, options) accepts any workbook-like object with workbook.xlsx.writeBuffer() and workbook.xlsx.load(...), which matches ExcelJS workbooks.

recalculateExceljsBuffer(input, options) accepts XLSX bytes and returns the same result shape as xlsx-formula-recalc.

Cell targets must be sheet-qualified A1 references such as Inputs!B2 or 'Pricing Model'!F12.

Scope

Use this when a Node service already uses ExcelJS for workbook I/O but needs deterministic formula readback after changing inputs. It is not a full Excel clone: unsupported Excel functions, external workbook links, macros, and volatile functions may need review. Import warnings are returned in result.warnings.