JavaScript modules will often export arbitrary static objects for use withtheir provided interfaces. These objects can be accessed from Rust by declaringa namedstatic in theextern block with an#[wasm_bindgen(thread_local_v2)] attribute.wasm-bindgen will bind aJsThreadLocal for these objects, which can be cloned into aJsValue.

These values are cached in a thread-local and are meant to bind static valuesor objects only. For getters which can change their return value or throw seehow to import getters.

For example, given the following #"#optional-statics">

Optional statics

If you expect the JavaScript value you're trying to access to not always beavailable you can useOption<T> to handle this:

# #![allow(unused_variables)]#fn main() {extern "C" {    type Crypto;    #[wasm_bindgen(thread_local_v2, js_name = crypto)]    static CRYPTO: Option<Crypto>;}#}

Ifcrypto is not declared or nullish (null orundefined) in JavaScript,it will simply returnNone in Rust. This will also account for namespaces: itwill returnSome(T) only if all parts are declared and not nullish.

Strings can be imported to avoid going throughTextDecoder/Encoder when requiring just aJsString. This can be useful when dealing with environments whereTextDecoder/Encoder is not available, like in audio worklets.

# #![allow(unused_variables)]#fn main() {#[wasm_bindgen]extern "C" {    #[wasm_bindgen(thread_local_v2, static_string)]    static STRING: JsString = "a string literal";}#}