Node js deep file indexer module keeps processing sub files as if they are in main directory too

See more:

Javascript

Node.js

FileIO

I'm trying to make a file indexer by node.js. The program is supposed to index files and folders in an array and also check inside folders and add all sub folders and files

I wrote:

fs.readdir(__dirname,index);
function index(err,data){
 for (i in data){
        if(fs.statSync(data[i]).isDirectory()){
            j.folders.push(path.resolve(data[i]));
            fs.readdir(data[i],index);
        }
        else{
            j.files.push(path.resolve(data[i]));
        }
    }
} 

... this code, but when it passes inside a folder it gives traceback and stops executing.

ps. please don't comment about walk, I want to write my own module.