Function js_sys::Atomics::add_bigint

pub fn add_bigint(
    typed_array: &JsValue,
    index: u32,
    value: i64
) -> Result<i64, JsValue>

The static Atomics.add() method adds 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.

This method is used to operate on a BigInt64Array or a BigUint64Array.

MDN documentation