Architecture

Layer Diagram

 ┌──────────────────────────────────────────┐
 │ TypeScript API │
 │ Workbook · Worksheet · Cell │
 │ StyleBuilder · RichTextBuilder │
 │ Utilities (dates, cell refs, CSV, JSON) │
 └────────────────┬─────────────────────────┘
 │ JSON string
 ┌────────────────┴─────────────────────────┐
 │ WASM Bridge (wasm-bindgen) │
 │ read() · write() · readJson() │
 └────────────────┬─────────────────────────┘
 │
 ┌────────────────┴─────────────────────────┐
 │ Rust Core (modern-xlsx-core) │
 │ ZIP (deflate) · XML (quick-xml SAX) │
 │ SharedStringTable · Style resolution │
 │ Content types · Relationships │
 └──────────────────────────────────────────┘

Data Flow

Reader Path

Uint8Array → WASM read()
 → ZIP decompress (zip crate)
 → Parse XML parts (quick-xml SAX)
 → Build WorkbookData struct
 → Serialize to JSON (serde_json)
 → JSON.parse() in JS
 → Workbook class wraps raw data

Writer Path

Workbook.toBuffer()
 → Serialize to JSON (JSON.stringify)
 → WASM write()
 → Build SST from shared string cells
 → Generate XML parts (quick-xml Writer)
 → ZIP compress (zip crate, deflate)
 → Return Uint8Array

Why JSON Bridge?

Rust Core Modules

OOXML Parsers

Performance Patterns

Bundle Size