docs.sheetjs.com/docz/docs/03-demos/42-engines/21-boa.md

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Rusty Sheets with Boa	Rust + Boa	demos/bigdata/index	solutions/input

import current from '/version.js'; import CodeBlock from '@theme/CodeBlock';

:::danger pass

In a production application, it is strongly recommended to use a binding for a more performant engine like v8

:::

Boa is a JavaScript engine written in Rust.

SheetJS is a JavaScript library for reading and writing data from spreadsheets.

The "Complete Example" section creates a command-line tool for reading data from spreadsheets and generating CSV rows.

Integration Details

Initialize Boa

A JS context can be constructed in one line:

/* initialize */
let context = &mut boa_engine::Context::default();

The following helper function evaluates strings as JS code:

/* simple wrapper to evaluate code snippets */
fn eval_code(c: &mut boa_engine::Context, code: &str) -> Result<std::string::String, boa_engine::JsError> {
  let src = boa_engine::Source::from_bytes(code);
  match c.eval(src) {
    Ok(res) => { return Ok(res.to_string(c).unwrap().to_std_string_escaped()); }
    Err(e) => { return Err(e); }
  };
}

Load SheetJS Scripts

The SheetJS Standalone scripts can be parsed and evaluated in a Boa context.

Boa provides a special helper boa_engine::Source::from_filepath to read source code from a path, but it is recommended to inline the SheetJS standalone script using the include_str! macro:

  /* load library */
  match eval_code(context, include_str!("../xlsx.full.min.js")) {
    Ok(_res) => {}
    Err(e) => { return eprintln!("Uncaught {e}"); }
  }

To confirm the library is loaded, XLSX.version can be inspected:

  /* get version string */
  match eval_code(context, "XLSX.version") {
    Ok(res) => { println!( "SheetJS library version {}", res); }
    Err(e) => { return eprintln!("Uncaught {e}"); }
  }

Reading Files

Boa supports ArrayBuffer natively. This snippet reads data from a file into Vec<u8> and stores the data as an ArrayBuffer in global scope:

  /* read file */
  let data: Vec<u8> = std::fs::read("pres.xlsx").unwrap();
  let array: boa_engine::object::builtins::JsArrayBuffer = boa_engine::object::builtins::JsArrayBuffer::from_byte_block(file, context).unwrap();
  let attrs = boa_engine::property::Attribute::WRITABLE | boa_engine::property::Attribute::ENUMERABLE | boa_engine::property::Attribute::CONFIGURABLE;
  let _ = context.register_global_property(boa_engine::js_string!("buf"), array, attrs);

  /* parse with SheetJS */
  match eval_code(context, "void (globalThis.wb = XLSX.read(buf))") {
    Ok(_res) => { }
    Err(e) => { return eprintln!("Uncaught {e}"); }
  }

wb will be a variable in the JS environment that can be inspected using the various SheetJS API functions.

Complete Example

:::note Tested Deployments

This demo was tested in the following deployments:

Architecture	Boa	Date
darwin-x64	0.20.0	2025-03-31
darwin-arm	0.20.0	2025-02-13
win11-x64	0.20.0	2025-04-28
win11-arm	0.20.0	2025-02-23
linux-x64	0.20.0	2025-04-21
linux-arm	0.20.0	2025-02-15

:::

0. Install Rust.

:::caution pass

Boa 0.18.0 requires Rust version 1.67 or later.

Debian 12 (Bullseye) ships with Rust version 1.63.0.

It is strongly recommended to install Rust from the official distribution.

:::

1. Create a new project:

cargo new sheetjs-boa
cd sheetjs-boa
cargo run

2. Add the boa_engine crate:

cargo add boa_engine

3. Download the SheetJS Standalone script and test file. Save both files in the project directory:

• xlsx.full.min.js
• pres.xlsx

{\ curl -LO https://cdn.sheetjs.com/xlsx-${current}/package/dist/xlsx.full.min.js curl -LO https://docs.sheetjs.com/pres.xlsx}

:::caution pass

PowerShell curl is incompatible with the official curl program. The command may fail with a parameter error:

Invoke-WebRequest : A parameter cannot be found that matches parameter name 'LO'.

curl.exe must be used instead:

{\ curl.exe -LO https://cdn.sheetjs.com/xlsx-${current}/package/dist/xlsx.full.min.js curl.exe -LO https://docs.sheetjs.com/pres.xlsx}

:::

4. Download main.rs and replace src/main.rs:

curl -L -o src/main.rs https://docs.sheetjs.com/boa/main.rs

:::caution pass

PowerShell curl is incompatible with the official curl program. The command may fail with a parameter error:

Invoke-WebRequest : A parameter cannot be found that matches parameter name 'LO'.

curl.exe must be used instead:

curl.exe -L -o src/main.rs https://docs.sheetjs.com/boa/main.rs

:::

5. Build and run the app in release mode:

cargo run --release pres.xlsx

After a short wait, the contents will be displayed in CSV form.

:::caution pass

The default debug build is not optimized and can elicit stack overflow errors. It is strongly encouraged to use --release when possible.

:::