Atomics.sub()

// Create a SharedArrayBuffer with a size in bytes
const buffer = new SharedArrayBuffer(16);
const uint8 = new Uint8Array(buffer);
uint8[0] = 7;
// 7 - 2 = 5
console.log(Atomics.sub(uint8, 0, 2));
// Expected output: 7
console.log(Atomics.load(uint8, 0));
// Expected output: 5

Atomics.sub(typedArray, index, value)

const sab = new SharedArrayBuffer(1024);
const ta = new Uint8Array(sab);
ta[0] = 48;
Atomics.sub(ta, 0, 12); // returns 48, the old value
Atomics.load(ta, 0); // 36