nodejs中__filename和__dirname的区别

　　在Node-API里面对二者的解释是：

__filename 

 

The filename of the code being executed. This is the resolved absolute path of this code file. For a main program this is not necessarily the same filename used in the command line. The value inside a module is the path to that module file.

Example: running node example.js from /Users/mjr

console.log(__filename);
// /Users/mjr/example.js

__filename isn't actually a global but rather local to each module.

 

__dirname 

 

The name of the directory that the currently executing script resides in.

Example: running node example.js from /Users/mjr

console.log(__dirname);
// /Users/mjr

__dirname isn't actually a global but rather local to each module.

　　这大概的意思就是，__filename指的是当前解析文件的实际物理地址，而__dirname指的是此文件在被执行时所在的地址

 

　 　具体的可以通过下面两个代码来看

　　test.js

var text = require("./test2");
console.log("the test.js's filename is: %s",__filename);
console.log("the test.js's dirname is %s",__dirname);
text.start();

　　test2.js

function start(){
    console.log("the test2.js's filename is: %s",__filename);
    console.log("the test2.js's dirname is %s",__dirname);
}
exports.start = start;

在这里，test.js  require了 test2.js，二者是在同一个目录下面

然后我们执行node test.js

结果是：

the test.js's filename is: /home/xing/ANodeJsWebSite/node/test.js
the test.js's dirname is /home/xing/ANodeJsWebSite/node
the test2.js's filename is: /home/xing/ANodeJsWebSite/node/test2.js
the test2.js's dirname is /home/xing/ANodeJsWebSite/node

然后我们把test2.js移到上层目录，更改一下test.js里面的require地址，再运行test.js

the test.js's filename is: /home/xing/ANodeJsWebSite/node/test.js
the test.js's dirname is /home/xing/ANodeJsWebSite/node
the test2.js's filename is: /home/xing/ANodeJsWebSite/test2.js
the test2.js's dirname is /home/xing/ANodeJsWebSite

可见__filename始终是用绝对路径显示一个文件的位置，而__dirname则是该文件所在目录的绝对路径