wasm-bindgen/guide/src/reference/attributes/on-js-imports/js_namespace.md

js_namespace = blah

This attribute indicates that the JavaScript type is accessed through the given namespace. For example, the WebAssembly.Module APIs are all accessed through the WebAssembly namespace. js_namespace can be applied to any import (function or type) and whenever the generated JavaScript attempts to reference a name (like a class or function name) it'll be accessed through this namespace.

#[wasm_bindgen]
extern "C" {
    #[wasm_bindgen(js_namespace = console)]
    fn log(s: &str);
    
    type Foo;
    #[wasm_bindgen(constructor, js_namespace = Bar)]
    fn new() -> Foo;
}

log("hello, console!");
Foo::new();

This is an example of how to bind namespaced items in Rust. The log and Foo::new functions will be available in the Rust module and will be invoked as console.log and new Bar.Foo in JavaScript.