Excel
Reading Excel in the Browser With SheetJS Without a Server
Parse an uploaded Excel file in the browser with SheetJS: read it, pick a sheet, convert to JSON, handle dates, limits and security, then export a workbook.
7 min read
Tag
javascript
17 posts
Excel
Reading Excel Files in Node With exceljs Step by Step
Read and write xlsx in Node.js with exceljs: load a workbook, read typed cells, handle formulas and dates, stream large sheets and avoid common traps.
7 min read
XML
Parsing XML in Node With fast xml parser and Its Defaults
fast-xml-parser returns objects, but its defaults drop attributes and turn 007 into 7 and 29.50 into 29.5. Set the options, validate, and see the 4.4 s cost.
6 min read
XML
Parsing XML in JavaScript With DOMParser in the Browser
DOMParser reads XML in the browser but reports errors as a parsererror element, not an exception. Query with XPath, handle namespaces, compare with HTML mode.
6 min read
JSON
JSON parse and stringify Options You Probably Missed
The extra arguments of JSON.stringify and JSON.parse, tested in Node 24: toJSON, replacer arrays, indent limits, call order and exact numbers.
9 min read
JSONGuide
JSON in JavaScript and Node Done Carefully and Correctly
A tested guide to JSON in JavaScript and Node 24: what stringify drops, parse errors, big numbers, dates, circular data, cloning, files and large inputs.
20 min read
CSV
Fixing Garbled Characters in a Downloaded CSV From a Web App
A CSV from your web app opens as Zoë in Excel. Check the bytes, the charset header and the BOM the server sends, then fix Express, Blobs and file names.
8 min read
CSV
Writing CSV From an Array of Objects in JavaScript
Turn an array of objects into CSV in JavaScript by hand or with csv-stringify: quoting, dates, booleans, formulas, BOM and a streaming writer.
9 min read
CSV
Streaming a Huge CSV Into a Database From Node the Fast Way
Load 2,000,000 CSV rows into PostgreSQL and SQLite from Node and compare per-row inserts, batches, transactions and COPY, with timings and failure behavior.
10 min read
CSV
Converting CSV to JSON in Node With a Few Lines of Code
Convert a CSV to JSON or NDJSON in Node with csv-parse, keep ZIP codes as text, and stream 2,000,000 rows at 120 MB instead of 1.6 GB.
8 min read
CSV
Why Splitting CSV by Comma in JavaScript Goes Wrong
line.split(',') breaks on quoted commas, quotes, line breaks and CRLF. See the failures, why the regex fix is slow, and a 30 line parser that works.
7 min read
CSV
Generating a CSV Download From JavaScript in the Browser
Build a CSV string, wrap it in a Blob and trigger a download with an object URL. Covers escaping, the Excel BOM, formula guards and how 1,000,000 rows behave.
9 min read