How to bind window global object?

[nikolajevs86]

Hi, sorry this maybe a stupid question, but I am stuck for several weeks already.
I have a global object with name SDK, which I can see that exists, but I cannot cast it.
I need to call some methods of this SDK object, so I am trying to bind it by:

#[wasm_bindgen]
extern "C" {
#[wasm_bindgen()]
    pub type SDK;

    #[wasm_bindgen(method)]
    pub fn start(this: &SDK);
}

pub fn execute() {
    let sdk_js_value = JsValue::from_str("SDK");
    
    if js_sys::Reflect::has(&js_sys::global(), &sdk_js_value).unwrap() {
        log!("SDK exists");        

        let sdk = js_sys::global().dyn_into::<SDK>().ok().unwrap(); // Here error is thrown
        sdk.start();
    } else {
        log!("SDK does not exists");
    }
}

It fail to cast to SDK object and I am not sure why it cannot do it. Can someone suggest something please?

[Liamolucko]

It's possible to get it to work the way you're trying to do it, getting the SDK from js_sys::global and then casting it, but I'd recommend doing it this way instead.

You can import methods from SDK by adding js_namespace = SDK to a regular function import:

use wasm_bindgen::prelude::*;

#[wasm_bindgen]
extern "C" {
    #[wasm_bindgen(js_namespace = SDK)]
    fn start();
}

pub fn execute() {
    if js_sys::Reflect::has(&js_sys::global(), &JsValue::from_str("SDK")).unwrap() {
        log!("SDK exists");

        start();
    } else {
        log!("SDK does not exists");
    }
}

Calling start will run SDK.start() on the JS side.

[nikolajevs86]

It works, it appeared so easy, thanks a lot!
Just to sum up, so by this approach we are mapping js function of global SDK object, but if we want to use this SDK object properties then we need to cast it to the object using dyn_into, right?

[Liamolucko]

Yes, you would need to get a reference to the actual SDK object to get at its properties. Retrieving it from js_sys::global() and using dyn_into is one way to do that, but you can also get at the object by using a static:

use wasm_bindgen::prelude::*;

#[wasm_bindgen]
extern "C" {
    type Sdk;

    #[wasm_bindgen(method, getter)]
    fn property(this: &Sdk) -> String;

    static SDK: Sdk;
}

pub fn execute() {
    let x = SDK.property();
}