go install github.com/jcbhmr/gojs/cmd/...@latestYou can run the output JavaScript in any ECMAScript 2020 environment that implements the Web Assembly JavaScript Interface. That includes Node.js, the browser, Deno, Bun, and more.
The following optional features may enhance your Go JavaScript WebAssembly app:
- Console
- Fetch Standard
node:fsnode:processnode:child_processnode:net
If you're in the browser and want to provide some polyfills for these features you may do so using a pattern like this:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<script type="importmap">
{
"scopes": {
"./app.js": {
"node:fs": "./my-fs.js",
"node:process": "./my-process.js"
}
}
}
</script>
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>My Go WebAssembly App</title>
<script type="module" src="app.js"></script>
</head>
<body>
<p>The file contents should be printed below</p>
<pre id="file-contents">This text should be replaced by Go code!</pre>
</body>
</html>Go JavaScript WebAssembly programs are always linear; they still have a main()
and an exit code. However you can call exported functions from JavaScript if
you use a hack like this:
var jsSayHello = js.FuncOf(func(this js.Value, args []js.Value) any {
fmt.Println("Hello from Go!")
return js.Undefined()
})
var jsExit = js.FuncOf(func(this js.Value, args []js.Value) any {
os.Exit(0)
return js.Undefined()
})
func main() {
importMetaURL, err := url.parse(js.ImportMeta().Get("url").String())
jsDeferred := js.Global().Get(importMetaURL.Fragment)
jsExports := js.ValueOf(map[string]any{
"sayHello": jsSayHello,
"exit": jsExit,
})
jsDeferred.Call("resolve", jsExports)
select{} // Lazy wait forever.
}globalThis.abc123 = Promise.withResolvers();
// Notice how we are NOT awaiting the promise returned by `import()`?
import("./app.js#abc123").catch(globalThis.abc123.reject);
const lib = await globalThis.abc123.promise;
delete globalThis.abc123;
lib.sayHello();
lib.exit();
// Now the Go program has exited and we can't call into it anymore.
// 🛑 Error: Program has exited.
lib.sayHello();This project is a mix of three projects that share the same root folder:
- An npm project that uses Vite to compile a bunch of nice TypeScript into
a single
gort0*file - A Go project CLI wrapper around
gothat setsGOOS=js, setsGOARCH=wasm, and links the output WebAssembly with thegort0*runtime - A Go package collection that re-implements parts of the Go standard library to use JavaScript APIs