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

# #![allow(unused_variables)]
#fn main() {
#[wasm_bindgen(module = "wu/tang/clan")]
extern "C" {
    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,

# #![allow(unused_variables)]
#fn main() {
#[wasm_bindgen]
extern "C" {
    fn illmatic() -> u32;
}
#}

generates JavaScript import glue like:

let illmatic = this.illmatic;

Note that if the string specified with module starts with ./, ../, or / then it's interpreted as a path to a local JS snippet. If this doesn't work for your use case you might be interested in the raw_module attribute