1.require.main.filename
var path = require('path');
var appDir = path.dirname(require.main.filename);
2.global.X
// index.js
var path = require('path');
global.appRoot = path.resolve(__dirname);
// lib/moduleA/component1.js
require(appRoot + '/lib/moduleB/component2.js');
3.process.cwd（）
$ cd /home/demo/
$ mkdir subdir
$ echo "console.log(process.cwd());" > subdir/demo.js
$ node subdir/demo.js
/home/demo
$ cd subdir
$ node demo.js
/home/demo/subdir
4.app-root-path
使用该包 https://github.com/inxilpro/node-app-root-path