Update an Excel table from CSV in the browser

Parse fresh CSV data, replace an existing Excel table, validate the workbook, and create a local download.

This pattern is useful when an Excel-authored report or template must keep its formulas, styles, charts, macros, and unrelated worksheets while one data table is refreshed.

Use the free Excel Table Refresher for the finished workflow, or build it into your own application with @ironsheet/browser.

import {
  inspectWorkbookArchiveFromBlob,
  openWorkbookFromBlob,
  writeWorkbookToBlobSafely
} from "@ironsheet/browser";

const archive = await inspectWorkbookArchiveFromBlob(workbookFile);
if (!archive.accepted) {
  throw new Error(archive.issues[0]?.message);
}

const workbook = await openWorkbookFromBlob(workbookFile);
const table = (await workbook.tables()).find(
  (candidate) => candidate.name === "RevenueTable"
);
if (table === undefined) {
  throw new Error("RevenueTable was not found");
}

await workbook.replaceTableRows("RevenueTable", csvRows);

const result = await writeWorkbookToBlobSafely(workbook);
if (!result.wrote || result.blob === undefined) {
  throw new Error("Ironsheet refused to create an invalid workbook");
}

const downloadUrl = URL.createObjectURL(result.blob);

Run the workbook work in a Web Worker when tables may be large. Transfer the input ArrayBuffer into the worker, keep CSV values beginning with = as strings unless formulas are explicitly intended, and revoke the temporary Blob URL after the download is complete.