This won't work on OS X due to lack of library support. Can I suggest something like this?

#ifdef _WIN32
  Sleep(1000);
#else
  sleep(1);
#endif

I am happy to use that.

But since the latest v8 is also using c++11, I think OS X might be able to get around c++11 problems by using new compilers and libraries.

There are two aspects to C++11 support: compiler support (okay on OS X) and libc++ support (which is lacking.)

I noticed the default libc++ library on OS X is outdated and doesn't support c++11. I wonder how OS X user compile the latest v8, which is part of nodejs and using c++11? they should have a solution to that. (I think they download the lib from somewhere)

That's right, it ships with its own copy of libc++: https://chromium.googlesource.com/chromium/buildtools/+/master/third_party/libc++/