What does "this" mean in a nodejs module?

Codes like the following:

var fs = require('fs');//.etc
//{}
console.log(this);

module.exports = {sayyou:1,sayme:2};

I know that "global" is the default context as 'window' in browser,but what is the 'this'?

this (in the context of a module) is the same as exports in node.js. However you should generally use exports/module.exports instead, so that it's explicitly clear what you're modifying.