serde_wasm_bindgen has various options to change the behavior of the translation between rust and javascript. It would be useful to expose them through attributes on the macro.

Notably:

• serialize_missing_as_null: Option<T> is T | null instead of T?
• serialize_maps_as_objects: HashMap<K, V> is Record<K, V> instead of Map<K, V>
• serialize_large_number_types_as_bigints: {u,i}{64,size} translates to bigint instead of number
• serialize_bytes_as_arrays: ByteBuf translates to number[] instead of Uint8Array