Function js_sys::Atomics::sub

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

The static Atomics.sub() method subtracts 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 sub_bigint to operate on a BigInt64Array or a BigUint64Array.

MDN documentation