Function js_sys::Atomics::or

pub fn or(typed_array: &JsValue, index: u32, value: i32) -> Result<i32, JsValue>

The static Atomics.or() method computes a bitwise OR with a given value at a given position in the array, and returns the old value at that position. This atomic operation guarantees that no other write happens until the modified value is written back.

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

MDN documentation