Javascript 在nodejs中导出变量和函数

我试图在nodejs中将一组全局变量和函数从一个Javascript文件导出到另一个Javascript文件

从 节点js.include.js

var GLOBAL_VARIABLE = 10;

exports.GLOBAL_VARIABLE = GLOBAL_VARIABLE;

module.exports = {

    add: function(a, b) {
        return a + b;
    }

};

进入测试节点js include.js：

var includes = require('./node-js-include');

process.stdout.write("We have imported a global variable with value " + includes.GLOBAL_VARIABLE);

process.stdout.write("\n and added a constant value to it " + includes.add(includes.GLOBAL_VARIABLE, 10));

但是变量；我得到以下输出：

We have imported a global variable with value undefined
 and added a constant value to it NaN

为什么不导出全局变量？

2种解决方法：

module.exports.GLOBAL_VARIABLE = GLOBAL_VARIABLE;

module.exports.add: function(a, b) {
    return a + b;
};

---

可能重复的

module.exports.GLOBAL_VARIABLE = GLOBAL_VARIABLE;

module.exports = { 
    add: function(a, b) {
        return a + b;
    }, 
    GLOBAL_VARIABLE: GLOBAL_VARIABLE
};