v1.0.0 — Stable Release

First stable release. API frozen, production-ready.

Install

npm install modern-xlsx

Highlights

• 10 Chart Types — bar, column, line, pie, doughnut, scatter, area, radar, bubble, stock with fluent ChartBuilder API
• Formula Engine — 54 built-in Excel functions (SUM, VLOOKUP, IF, INDEX/MATCH, etc.)
• Encryption — Read/write password-protected files (ECMA-376 Standard & Agile AES-256)
• Pivot Tables — Full read/write with PivotTableBuilder API
• Threaded Comments — Modern Excel comment threads with reply support
• Slicers & Timelines — Interactive filtering controls (read/write)
• Streaming Writer — 100K+ row output with O(unique strings) memory
• Rich Text — RichTextBuilder for inline cell formatting with full roundtrip
• Image Embedding — PNG/JPEG support in worksheets
• CLI Tool — modern-xlsx info and modern-xlsx convert
• Error System — ModernXlsxError with 18 machine-readable error codes

Full Feature Set

Everything SheetJS Pro charges for — free and open source:

Performance

Stats

• Rust: 424 tests (402 unit + 12 golden + 5 security + 4 bench + 1 doctest)
• TypeScript: 1,287 tests across 58 files
• WASM binary: ~2.0 MB (1.1 MB with lite build)
• Zero runtime dependencies

Links

• npm
• Documentation
• Wiki
• Full Changelog

v1.0.0-rc.1 — Release Candidate 1

API frozen, production-ready feature set. All tests passing.

Highlights

New Features

• PivotTableBuilder — fluent builder API following the ChartBuilder pattern
• Auto-Filter Custom Filters — CustomFilterData/CustomFiltersData with full roundtrip
• Page Breaks — PageBreaksData with row/column break parsing, writing, and convenience methods
• Rich Text Cells — Cell.richText getter/setter, RichTextBuilder fluent API, full WASM roundtrip
• Image Embedding — PNG/JPEG support in worksheets
• Error System — ModernXlsxError class with fromWasmError() parser and 18 machine-readable error codes

Improvements

• API Audit — naming consistency, parameter types, return types across all public APIs
• JSDoc Coverage — comprehensive documentation across 11 source files with @example tags
• README — 5-line quick start, improved onboarding
• Error Messages — context-rich, actionable errors across Rust core (ZIP, XML, OLE2, cell, style)
• Expanded Builders — ChartBuilder, StyleBuilder with additional JSDoc and methods

Verification

• Rust: 424 tests (402 unit + 12 golden + 5 security + 4 bench + 1 doctest), clippy clean
• TypeScript: 1287 tests across 58 files, typecheck clean
• WASM binary: ~2.0 MB

Audit Reports

• API Surface Audit — 6 critical, 7 important, 11 minor findings for post-RC
• Rust Code Audit — safety (as casts in OLE2), performance (writer rels re-parsing), modernization
• TypeScript Code Audit — dedup opportunities (wasm-loader), helper extraction, error class consistency

Full Changelog: v0.9.2...v1.0.0-rc.1

What's New

Streaming XLSX Writer

• StreamingXlsxWriter for writing 100K+ row files with O(unique strings) memory
• Backed by Rust/WASM StreamingWriterCore with incremental ZIP entry writing
• Methods: create(), startSheet(), writeRow(), setStylesXml(), finish()

Pivot Table / Slicer / Timeline Write APIs

• Pivot Tables: ws.addPivotTable(), ws.removePivotTable(), wb.addPivotCache(), wb.addPivotCacheRecords()
• Slicers: ws.addSlicer(), ws.removeSlicer(), wb.addSlicerCache()
• Timelines: ws.addTimeline(), ws.removeTimeline(), wb.addTimelineCache()
• New types: PivotCacheDefinitionData, PivotCacheRecordsData, discriminated CacheValue unions

WASM Lite Build

• Feature-gated encryption for smaller WASM binary via modern-xlsx/lite import

Parser Refactoring

• worksheet/parser.rs reduced from 2,891 → 2,202 lines
• 20 extracted helper functions for XML attribute parsing

CLI Modernization

• Node 24 parseArgs() + async node:fs/promises

Security & Documentation

• Comprehensive ECMA-376 crypto audit (docs/SECURITY-AUDIT.md)
• Interactive demo site + 4 example projects (sales report, CSV converter, encrypted payroll, chart dashboard)
• Deno/Bun compatibility test harnesses
• CHANGELOG.md with full version history

Verification

• 406 Rust tests — all passing
• 1,259 TypeScript tests across 57 files — all passing
• Clippy clean, TypeScript typecheck clean, Biome lint clean

35-Point Improvement Release

Rust Performance

• ryu crate for 2-6x faster f64 formatting in XML/JSON hot paths
• Byte-level JSON escaping — scans bytes and batch-copies non-escape slices instead of per-char iteration
• make_rid() helper with itoa::Buffer — eliminated 21 format!() heap allocations in writer
• Cow<'static, str> on Relationship fields — zero-allocation for static OOXML constants
• From<serde_json::Error> for ModernXlsxError — 16 .map_err() calls replaced with plain ?
• if-let chains (Rust 2024 edition idiom)

Rust Code Organization

• Split worksheet.rs (7,173 lines) → worksheet/{mod,parser,writer,json}.rs
• Split charts.rs (4,862 lines) → charts/{mod,types,parser,writer}.rs
• Removed unused serde-wasm-bindgen dependency
• Added --vacuous-drops to wasm-opt flags

TypeScript Performance & Quality

• Split barcode.ts (1,828 lines) → 11 tree-shakeable codec modules
• O(1) sheet name cache via Map<string, number> in Workbook
• Discriminated union types for Worker messages (type-safe exhaustive switching)
• Replaced custom at() helpers with native methods
• Eliminated production as type casts
• Vitest pool: forks → threads (faster test execution)

CI/CD

• Security scanning: cargo-audit + npm audit in every CI run
• WASM binary size tracking with >2MB warning threshold
• Matrix testing: Node 24 + 25 ×ばつ ubuntu + windows (4 combinations)
• WASM artifact caching keyed on Cargo.lock + Rust sources

GitHub Presence

• Added dependabot.yml (Cargo + npm + GitHub Actions, weekly)
• Added CODEOWNERS, FUNDING.yml
• Fixed documentation: test counts, Rust version, SECURITY.md version table
• Added v0.9.0 feature documentation (pivot tables, threaded comments, slicers, timelines, CLI)

Verification

• 389 Rust tests — all passing, clippy clean (0 warnings)
• 1,230 TypeScript tests — all passing across 55 test files
• TypeScript typecheck: 0 errors
• Biome lint: 0 errors

Full Changelog: v0.9.0...v0.9.1

What's New

Pivot Tables (read-only)

Full OOXML pivot table parsing — definitions, fields, axes, items, subtotals, cache definitions, and cache records. Access via ws.pivotTables.

Threaded Comments (read + write)

Modern Excel threaded comments with person management. Create new threads with ws.addThreadedComment() and reply with ws.replyToComment().

Slicers (read-only)

Slicer definitions and caches for pivot table filtering. Access via ws.slicers.

Timelines (read-only)

Timeline definitions and caches for date-based pivot filtering. Access via ws.timelines.

CLI Tool

npx modern-xlsx info report.xlsx # sheet names, dimensions, row counts
npx modern-xlsx convert data.xlsx out.json # XLSX → JSON
npx modern-xlsx convert data.xlsx out.csv --sheet 0 --format csv

Performance

• XML writer buffer pre-allocation for faster writes
• 4-8x faster than SheetJS for bulk read/write operations
• Honest benchmarks: SheetJS is faster for cell-by-cell writes and small utility conversions

Feature-Gated WASM

encryption and charts Cargo features — opt out of crypto deps for smaller WASM bundles.

API Improvements

• ModernXlsxError with .code property for structured error handling
• Readonly arrays throughout the API
• ws.dimension and ws.rowCount getters

Codebase Quality

• Full Rust 1.95 modernization (cold_path(), .find(), #[inline])
• TypeScript 6.0 patterns (satisfies, type guards)
• Zero clippy warnings

Stats

• 389 Rust tests | 1,230 TypeScript tests | 55 test files
• All passing ✅

Full Changelog: v0.8.6...v0.9.0

Rust 1.95 Modernization

Deep Rust modernization targeting Rust 1.95-beta features and idiomatic patterns across all 34 Rust source files (~30,760 lines).

Rust 1.95 Features

• core::hint::cold_path() on all error/panic branches (23 files) — compiler branch layout optimization
• rust-version bumped to 1.95.0 in workspace Cargo.toml

Iterator Modernization

• 58 single-attribute for loops replaced with .find() iterator pattern across all OOXML parsers
• 3 index-based loops replaced with zip() iteration in reader.rs
• next_r_id() extracted as method on Relationships — deduplicates closure + inline expression in writer.rs

Performance Annotations

• #[inline] on 3 hot-path streaming JSON helpers (worksheet.rs)
• #[inline] on 12 chart enum xml_val() methods (charts.rs)

Code Quality

• Shared serde helpers (is_false, is_true, default_true) extracted to ooxml/mod.rs — removes 22 lines of duplication across 5 files
• WASM bridge: parse_workbook() + to_js_err() helpers deduplicate 6 JSON parse patterns

Verification

• 357 Rust tests pass (340 unit + 12 golden + 5 security)
• 1210 TypeScript tests pass across 50 test files
• Zero clippy warnings

Full Changelog: v0.8.5...v0.8.6

Deep audit across the entire codebase: critical bug fixes, lint cleanup, Rust & TypeScript modernization, and expanded test coverage.

Bug Fixes

• CRITICAL: Merge image + chart drawing XML to prevent silent data loss when sheets have both images and charts
• Restore ChartAxis.fontSize with proper <c:txPr> writer/parser
• Parse oneCellAnchor charts from drawing XML (not just twoCellAnchor)
• Combo chart roundtrip — parse secondary_chart correctly
• WASM boundary validation for chart data before crossing to Rust

Rust Modernization

• Eliminated all panic!() calls in encryption — return Result instead
• Iterator combinators replace manual loops across charts, styles, tables, theme
• #[derive(Default)] on 7 builder structs, removing dead new() methods
• Let-else patterns, Option::take() for zero-clone operations
• Zero clippy warnings across entire codebase

TypeScript 6.0 Modernization

• satisfies operator for compile-time validation of constant maps
• readonly on 16 interface array fields for immutability safety
• Cached Intl.NumberFormat — 10x faster numeric formatting
• Single-pass escapeHtml — replaces 4-chained .replaceAll()
• Worker crash memory leak fix (pending promises rejected on terminate)
• ??= nullish coalescing assignment throughout
• Eliminated all 19 noNonNullAssertion lint errors with safe array accessors

Test Coverage

• Rust: 357 tests (expanded golden tests from 2 to 12 scenarios)
• TypeScript: 1,210 tests (added chart API, chart type, and roundtrip tests)
• Total: 1,567 tests

Full Changelog: v0.8.1...v0.8.5

Bug fixes from comprehensive v0.8.0 charts audit.

Rust Fixes

• CRITICAL: <drawing> now emitted before <tableParts> per ECMA-376 CT_Worksheet schema — fixes strict validator rejections when worksheets have both charts and tables
• CRITICAL: <c:style> now emitted before <c:chart> per CT_ChartSpace schema
• write_f64_element skips NaN/Infinity values (consistent with write_f64_json fix from v0.5.1)
• Remove dead ChartAxis.font_size field (was never parsed or written)
• DataLabelsBuilder::build_and_reset() uses Option::take() for zero-clone operation

TypeScript Fixes

• buildAxisTitle uses == null instead of !title (preserves empty string titles)
• Remove ChartAxisData.fontSize (dead field, matches Rust removal)
• Lint fixes: non-null assertions, formatting, cognitive complexity

Full Changelog: v0.8.0...v0.8.1

Charts & Visualizations

modern-xlsx now supports full chart creation, reading, and roundtrip — programmatically generate Excel charts with titles, legends, data labels, trendlines, and more.

New Features

Chart Data Model (0.8.0)

• 10 chart types: Bar, Column, Line, Pie, Doughnut, Scatter, Area, Radar, Bubble, Stock
• Full data model: ChartData, ChartSeries, ChartAxis, ChartLegend, DataLabels, ChartAnchor
• Serde roundtrip between Rust structs and JSON (WASM boundary)

Chart XML Writer (0.8.2–0.8.5)

• Complete ECMA-376 DrawingML Chart XML generation (c:chartSpace, c:chart, c:plotArea)
• All chart type elements: c:barChart, c:lineChart, c:pieChart, c:scatterChart, etc.
• Series with fill/line colors, markers, smooth lines, explosion (pie)
• Axis configuration: scaling (min/max/log), gridlines, tick marks, number formats, axis titles
• Chart titles with rich text formatting (bold, font size, color)
• Data labels: showVal, showCatName, showPercent, number format, leader lines
• Legend with position (top/bottom/left/right/topRight) and overlay
• Drawing anchors: xdr:twoCellAnchor with cell coordinates and EMU offsets

Chart Drawing & Packaging (0.8.4)

• xl/charts/chart{n}.xml ZIP entries with content types
• xl/drawings/drawing{n}.xml with chart anchors
• Drawing relationships (_rels) linking charts to drawings
• Worksheet <drawing r:id="..."/> reference
• Global chart numbering across sheets

TypeScript ChartBuilder API (0.8.6)

• Fluent builder: new ChartBuilder('bar').title('Sales').addSeries({...}).legend('bottom').build()
• Worksheet.addChart(type, configure) callback pattern
• Worksheet.charts getter, addChartData(), removeChart()
• Full axis configuration, data labels, scatter/radar styles, doughnut hole size

Chart XML Reader (0.8.7)

• Full SAX parser for chart XML → ChartData structs
• Drawing anchor parser for xdr:twoCellAnchor elements
• resolve_charts() two-step resolution: sheet.rels → drawing → chart
• Charts transition from opaque preserved_entries to structured typed data

Roundtrip & Style Presets (0.8.8)

• 7 end-to-end WASM write/read roundtrip tests
• CHART_STYLE_PALETTES — 8 predefined Excel color palettes
• getChartStylePalette(styleId) helper

Advanced Features (0.8.9)

• Trendlines: Linear, Exponential, Logarithmic, Polynomial, Power, Moving Average
• Error Bars: FixedVal, Percentage, StdDev, StdErr with direction (Both/Plus/Minus)
• 3D Rotation: rotX, rotY, perspective, right-angle axes
• Data Table: show data table below chart
• Combo Charts: secondary chart type + secondary value axis (via secondaryChart field)

Example

import { initWasm, Workbook, ChartBuilder } from 'modern-xlsx';
await initWasm();
const wb = new Workbook();
const ws = wb.addSheet('Sales');
// ... populate data ...
ws.addChart('bar', (b) => {
 b.title('Monthly Revenue', { bold: true, fontSize: 1400 })
 .addSeries({ name: 'Revenue', catRef: 'Sales!$A2ドル:$A13ドル', valRef: 'Sales!$B2ドル:$B13ドル', fillColor: '4472C4' })
 .catAxis({ title: 'Month' })
 .valAxis({ title: 'Amount ($)', majorGridlines: true, numFmt: '#,##0' })
 .legend('bottom')
 .grouping('clustered')
 .anchor({ col: 4, row: 0 }, { col: 14, row: 20 });
});
await wb.toFile('report.xlsx');

Stats

• Rust: 337 tests (330 unit + 2 golden + 5 security)
• TypeScript: 1171 tests across 47 files
• Zero clippy warnings, zero type errors

Comprehensive Codebase Audit

Bug fixes, security hardening, and precision improvements discovered through deep audit of every Rust and TypeScript file.

Rust Fixes

• JSON injection prevention — cell references in the streaming JSON path are now properly escaped via json_escape_to, preventing malformed JSON from adversarial XLSX files
• Whitespace preservation in SST — <t> elements in shared strings now include xml:space="preserve" when values start/end with whitespace, preventing Excel from stripping significant spaces
• Path traversal defense — resolve_relative_path no longer allows .. segments to escape below the root directory in crafted .rels targets
• Overflow protection — frozen pane topLeftCell computation uses saturating_add to prevent u32 overflow on adversarial input
• Writer performance — ZIP entries Vec capacity improved from 6 + sheets to 10 + sheets*3 + preserved, reducing reallocations for complex workbooks

TypeScript Fixes

• ROUND precision — ROUND(1.005, 2) now correctly returns 1.01 (fixed floating-point multiplication issue with epsilon adjustment)
• ROUND/ROUNDUP/ROUNDDOWN — negative fractional digit arguments now use Math.trunc instead of Math.floor, matching Excel semantics
• Cross-sheet ranges — resolveRange now propagates start.sheet to end.sheet, fixing silent wrong-sheet resolution for formulas like Sheet2!A1:B10
• Tokenizer — invalid exponents (e.g., 1e+) now backtrack instead of emitting NaN tokens
• sheetToJson — fixed off-by-one in collectRows that could include a spurious extra row past the data bounds
• SUMIF/COUNTIF — string criteria comparisons now use localeCompare for consistency with the formula evaluator

Stats

• 299 Rust tests + 1142 TypeScript tests passing
• Zero clippy warnings, zero lint errors, zero type errors

Full Changelog