Function store 

pub fn store<T>(typed_array: &T, index: u32, value: i32) -> Result<i32, JsValue>
where
    T: TypedArray + ErasableGenericBorrow<Int32Array>,

The static Atomics.store() method stores a given value at the given position in the array and returns that value.

You should use store_bigint to operate on a BigInt64Array or a BigUint64Array.

MDN documentation