as2wasm - Apache Royale Actionscript to WebAssembly Transpiler

0.1.5 verified Fri May 01 auth: no javascript

as2wasm is an Apache Royale tool that transpiles Actionscript (AS3) source code directly to WebAssembly (Wasm) modules. Version 0.1.5 is the latest stable release, part of the Apache Royale 0.9.x series. It enables running legacy Flash/Actionscript applications in modern browsers without the Flash plugin, targeting WebAssembly for near-native performance. Key differentiators: it is the only open-source AS3-to-Wasm transpiler, integrates with the Apache Royale framework for cross-platform UI compilation, and supports both ActionScript 3 and optional SWF input via a separate binary variant. Release cadence follows Apache Royale's quarterly releases.

Common errors

error Error: Cannot find module 'as2wasm' ↓

cause Package not installed or not in the node_modules path.

fix

Run npm install as2wasm (or yarn add as2wasm) in your project root.

error TypeError: as2wasm.compile is not a function ↓

cause Using the old `compile()` function name replaced in v0.1.3.

fix

Use compileString() instead of compile().

error SyntaxError: Octal literals are not allowed in strict mode in AS3 ↓

cause ActionScript code contains legacy octal literals (e.g., 0777) not supported in strict mode.

fix

Convert octal literals to decimal or hex (e.g., 0777 -> 511 or 0x1FF).

error Compile error: 'import' declarations may only appear at top level of a module ↓

cause Used ES module import syntax inside ActionScript code (file), but transpiler expects AS3 import.

fix

Use ActionScript import statements: import flash.display.Sprite;

error Wasm runtime error: out of memory (OOM) when allocating large string ↓

cause WebAssembly memory insufficient for large ActionScript objects.

fix

Increase initial memory size: compileString(code, { memory: { initial: 512 } }).

Warnings

breaking as2wasm v0.1.0 removed the SWF-to-Wasm pipeline; use apache-royale-0.9.x-bin-js-swf for SWF support. ↓

fix Install the SWF variant: npm install apache-royale-0.9.x-bin-js-swf or use the royale-asjs SWF build.

deprecated The function `compile()` was renamed to `compileString()` in v0.1.3. ↓

fix Replace calls to `compile()` with `compileString()`.

gotcha Module uses ES modules only; importing with CommonJS `require()` throws an error. ↓

fix Use dynamic import (e.g., `import('as2wasm')`) in Node.js or configure your bundler for ESM.

gotcha WebAssembly memory limit: AS3 strings and arrays may exceed default Wasm memory (64KB). ↓

fix Use the `memory` option: `compileString(code, { memory: { initial: 256, maximum: 512 } })`.

breaking v0.1.4 dropped support for ActionScript 2 compatibility flags; use AS3-only. ↓

fix Remove `-as2` or `--as2` flags in compile options; code must be AS3 compliant.

Install

npm install as2wasm

yarn add as2wasm

pnpm add as2wasm

Imports

transpile
wrong
```
const transpile = require('as2wasm').transpile;
```
correct
```
import { transpile } from 'as2wasm'
```
as2wasm is ESM-only; require() will not work. Use dynamic import or esbuild bundler.
compileFile
```
import { compileFile } from 'as2wasm'
```
Compiles a single .as file to Wasm bytes.

compileString

wrong

import compileString from 'as2wasm';

correct

import { compileString } from 'as2wasm'

Default export is not available; use named import.

version
```
import { version } from 'as2wasm'
```
Exports package version string for runtime checks.

Quickstart

Demonstrates compiling ActionScript files and strings to WebAssembly modules, then instantiating them.

import { compileFile, compileString, transpile } from 'as2wasm';

// Compile a .as file to Wasm
async function compileAsFile(inputFile) {
  const result = await compileFile(inputFile);
  console.log('Wasm module size:', result.byteLength);
  return result;
}

// Transpile inline ActionScript
const asCode = `
class HelloWorld {
  static function sayHello():String {
    return "Hello from AS3 in Wasm!";
  }
}
`;
const wasmModule = await compileString(asCode);
// wasmModule is a Uint8Array containing the Wasm binary

// Instantiate and use
const wasmInstance = await WebAssembly.instantiate(wasmModule);
const sayHello = wasmInstance.exports['HelloWorld.sayHello'];
console.log(sayHello()); // prints the string