code: function AtomicsFutexWaitJS(ia, index, value, timeout) {
    CheckSharedInteger32TypedArray(ia);
    index = ValidateIndex(index, %_TypedArrayGetLength(ia));
    if (IS_UNDEFINED(timeout)) {
      timeout = INFINITY;
    } else {
      timeout = TO_NUMBER(timeout);
      if (NUMBER_IS_NAN(timeout)) {
        timeout = INFINITY;
      } else {
        timeout = MaxSimple(0, timeout);
      }
    }
    return %AtomicsFutexWait(ia, index, value, timeout);
  }
docs: Futexes