how to add new proc macro to existing structure StructA and impl with wasm-bindgen so that we do not need create a new structure for StructA

To add a new proc macro to an existing structure StructA and impl with wasm-bindgen, you can simply add the proc macro as a new function or method within the impl block for StructA. This way, you do not need to create a new structure for StructA.

Here is an example code snippet to illustrate this:

#[wasm_bindgen]
struct StructA {
    data: Vec<u32>,
}

#[wasm_bindgen]
impl StructA {
    // existing methods for StructA

    #[wasm_bindgen(js_name = "newMethod")]
    pub fn new_method(&mut self, arg: u32) -> u32 {
        // implementation of the new method
        // use self.data and arg as needed

        // return a u32 value
        return some_value;
    }
}

In the example above, we have added a new method called new_method to the StructA impl block. We have also used the #[wasm_bindgen(js_name = "newMethod")] attribute to specify the JavaScript name for this method.

This new method can now be called in JavaScript as follows:

const structA = new StructA();
const result = structA.newMethod(42);

Note that you will need to rebuild and recompile your Rust code after adding the new proc macro