CODEWITHSUNDEEP
rustwebassemblywasm-bindgen
filiplitwora
filiplitwora

Reputation: 43

How to access JS object properties in Wasm (Rust)?

I'm using wasm bindgen and I have following function :

#[wasm_bindgen]
pub fn obj(o: &JsValue){
console::log_1(o);
}

and in js I call this function obj({name: "john"}); and it works fine, but when i try to console::log_1(o.name); it gives error unknown field pointing at name

Upvotes: 3

Views: 3402

Answers (2)

Maccesch
Maccesch

Reputation: 2128

There is a third variant: Use js_sys::Reflect::get.

In your case it would look like this:

let value = js_sys::Reflect::get(o, &"name".into())?;
console::log_1(value);

Please check the wasm_bindgen docs for Accessing Properties of Untyped JavaScript Values.

Upvotes: 3

Michael
Michael

Reputation: 2942

JsValue does not have a field name. To get this field you have to declare the JS object.

Variant 1

Add serde to your dependencies:

serde = "^1.0.101"
serde_derive = "^1.0.101"

Rust code:

extern crate serde;

#[derive(Serialize, Deserialize)]
pub struct User {
    pub name: String,
}

#[wasm_bindgen]
pub fn obj(o: &JsValue){
    let user: User = o.into_serde().unwrap();
    console::log_1(user.name);
}

Variant 2

Another way is to use wasm-bindgen directly but I never used it. It should work like this I think:

#[wasm_bindgen]
pub struct User {
    pub name: String,
}

#[wasm_bindgen]
pub fn obj(o: User){
    console::log_1(o.name);
}

Upvotes: 5

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