wasm-inliner

1.0.0 verified Mon Apr 27 auth: no javascript

Zero-config WASM to inline JS bundler. Version 1.0.0 converts a .wasm file into a standalone JavaScript file embedding the binary as Base64, eliminating the need for fetch, CORS headers, or separate hosting. Suitable for both browser and Node.js environments, it provides a simple init function to instantiate the module. Released as a CLI tool and library, it targets small WASM modules and prioritizes simplicity over complex build integration. Differentiates from full build systems like webpack/wasm-pack by being a single-purpose, no-config utility.

Common errors

error SyntaxError: Cannot use import statement outside a module ↓

cause The generated bundle uses ESM syntax but is loaded in a non-module script or CommonJS context.

fix

Add type="module" to your script tag, or use dynamic import() in Node.

error Error: WebAssembly.instantiate(): expected magic word 00 61 73 6d ↓

cause The .wasm file is corrupted or not a valid WebAssembly binary.

fix

Verify the .wasm file is correct and re-run the inliner on it.

Warnings

gotcha Generated bundle wraps WASM as Base64; large files increase JS size significantly. ↓

fix Only use for small WASM modules (<1MB). For larger files, prefer streaming compilation.

gotcha The generated bundle initializes WASM synchronously within the async init function, which may block the main thread if the WASM is large. ↓

fix Ensure initWasm() is called early and consider using Web Workers for heavy modules.

gotcha This tool does not handle WASM imports (e.g., environment, memory) beyond basic WASI stub. Complex WASM modules may fail. ↓

fix Pre-process your WASM to use simple exports/imports, or use a more comprehensive bundler like wasm-pack.

Install

npm install wasm-inliner

yarn add wasm-inliner

pnpm add wasm-inliner

Imports

initWasm
wrong
```
const initWasm = require('./your-file.bundle.js');
```
correct
```
import initWasm from './your-file.bundle.js';
```
Generated bundle exports a default async function. CJS require may work but is not officially supported; use ESM imports for browser compatibility.
cli (bin)
wrong
```
wasm-inliner your-file.wasm
```
correct
```
node bin/cli.js your-file.wasm
```
CLI is accessed via npx or global install; if not installed globally, run the script directly from the package.

Quickstart

Shows how to import the generated bundle and initialize the WASM module with a simple demo function call.

const initWasm = (await import('./your-file.bundle.js')).default;
const instance = await initWasm();
console.log(instance.add(5, 10));