Emscripten Library Generator

0.3.0 verified Fri May 01 auth: no javascript maintenance

The emscripten-library-generator (v0.3.0) converts normal JavaScript libraries into Emscripten's custom JS library format (.js) for use with the --js-library flag. It also auto-generates EXPORTED_FUNCTIONS lists via the --unresolved flag. Created by Emscripten author Evan Wallace, it resolves dependencies and prefixes symbols with underscores to match Emscripten's ABI. Development appears complete as of 2015; no recent releases. Unlike manual library authoring, it automates dependency resolution and underscore prefixing.

Common errors

error sh: emscripten-library-generator: command not found ↓

cause The tool is not installed globally or not in PATH.

fix

Run 'npm install -g emscripten-library-generator' and ensure npm global binaries are in PATH.

error Error: Cannot find module 'acorn' ↓

cause Missing dependency; old version of emscripten-library-generator may require acorn.

fix

Install acorn: 'npm install -g acorn' or install emscripten-library-generator locally and run via npx.

error SyntaxError: Unexpected token ... ↓

cause Input JavaScript uses ES6+ syntax not supported by the parser.

fix

Rewrite input files in ES5 syntax (no arrow functions, const/let, etc.).

Warnings

gotcha Top-level statements other than variable or function declarations are not supported. ↓

fix Put initialization code into a JavaScript function called as the first statement inside main() in C++.

gotcha All global symbols are automatically prefixed with an underscore to match Emscripten's output. ↓

fix In C++ code, use the underscore-prefixed names (e.g., _Foo_new) or use EXPORTED_FUNCTIONS with underscores.

gotcha The tool may not work with modern JavaScript features (ES6+). ↓

fix Use only ES5 syntax in input files.

Install

npm install emscripten-library-generator

yarn add emscripten-library-generator

pnpm add emscripten-library-generator

Imports

CLI tool
```
npm install -g emscripten-library-generator
```
This is a CLI tool, not a library. Install globally and run via emscripten-library-generator.

Quickstart

Shows installation and generation of an Emscripten library from a simple JS file with dependencies.

npm install -g emscripten-library-generator
echo 'var counter = 0;
function increment() {
  counter++;
  return counter;
}
function increment_double() {
  increment();
  return counter * 2;
}' > input.js
emscripten-library-generator input.js > library.js
cat library.js