What is it what determines whether JsValue gets returned or a more "precise" one like f64?

[ilyvion]

As an example, on window we have scroll_x() which returns Result<f64, JsValue> while inner_height() returns Result<::wasm_bindgen::JsValue, JsValue>.

Now, according to the docs inner_height is

An integer value indicating the window's layout viewport height in pixels. The property is read only¹ and has no default value.

I get that everything in JS is really f64, but still, sounds like this property could definitely return f64 instead of JsValue.

Footnotes

1. Despite this, web-sys exposes a set_inner_height for some reason. ↩