watever

0.5.2 verified Sat May 09 auth: no javascript

watever is a bundler and transpiler for WebAssembly text format (WAT) modules, enabling seamless integration with JavaScript. Version 0.5.2, active development. It statically links WAT modules, tree-shakes bytecode, and generates JS wrappers with ESM exports. Unlike other WASM tools, watever focuses on WAT-first development, allowing complex JS imports (e.g., strings, async functions) directly from WAT without glue code.

Common errors

error Error: Cannot find module 'watever' ↓

cause Global install not found or missing dependency

fix

Run 'npm install watever' locally and use 'npx watever'.

error TypeError: logNumber is not a function ↓

cause Forgot to await the async export

fix

Use 'await logNumber();' instead of 'logNumber();'.

error SyntaxError: Unexpected token 'export' ↓

cause Using require() on ESM-only generated module

fix

Use 'import' statement instead of require(), or rename file to .mjs.

Warnings

gotcha All exported functions become async due to WebAssembly.instantiate Promise ↓

fix Always use await when calling exported functions from JS.

breaking Import paths with '#lift' suffix changed semantics ↓

fix Use 'console.log#lift' instead of 'console.log' for lifted functions; see docs.

deprecated The --deno flag is experimental and may be removed ↓

fix Use Node.js for production; check Deno support status before using.

gotcha String encoding expects UTF-8, but WAT data defaults to ASCII ↓

fix Ensure string literals in WAT data sections are UTF-8 encoded, or use escape sequences for non-ASCII.

Install

npm install watever

yarn add watever

pnpm add watever

Imports

watever CLI
wrong
```
watever input.wat
```
correct
```
npx watever input.wat
```
CLI command, not a JS import. Use npx for global-less execution.

generated module

wrong

const { logNumber } = require('./log-number.wat.js')

correct

import { logNumber } from './log-number.wat.js'

Generated files are ESM-only; CJS require() fails.

default export
```
import mod from './mod.wat.js'
```
Default export is an object with all named exports. Available since v0.3.

Quickstart

Creates a WAT module with string import, bundles it, and calls the exported async function from JS.

// Install
npm install watever

// Create WAT file: helloworld.wat
(module
  (import "js" "console.log#lift" (func $log (param i32)))
  (import "watever/glue.wat" "lift_raw_string" (func $lift_raw_string (param i32 i32) (result i32)))
  (data (i32.const 0) "Hello, world!")
  (func $hello (export "helloWorld")
    (call $lift_raw_string (i32.const 0) (i32.const 13))
    call $log
  )
)

// Bundle
npx watever helloworld.wat

// Use generated JS module
import { helloWorld } from './helloworld.wat.js';
await helloWorld(); // "Hello, world!"