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

module = "blah"

The module attributes configures the module from which items are imported. For example,

#[wasm_bindgen(module = "wu/tang/clan")]
extern {
    type ThirtySixChambers;
}

generates JavaScript import glue like:

import { ThirtySixChambers } from "wu/tang/clan";

If a module attribute is not present, then the global scope is used instead. For example,

#[wasm_bindgen]
extern {
    fn illmatic() -> u32;
}

generates JavaScript import glue like:

let illmatic = this.illmatic;