I know it is a bit late to answer but I think my answer will help some visitors.
In Node.js you can easily get your current running file name and its directory by just using __filename and __dirname variables respectively.
In order to correct the forward and back slash accordingly to your system you can use path module of Node.js
var path = require('path');
Like here is a messed path and I want it to be correct if I want to use it on my server. Here the path module do everything for you
var randomPath = “desktop//my folder/\myfile.txt”;
var correctedPath = path.normalize(randomPath); //that's that
console.log(correctedPath);
desktop/my folder/myfile.txt
If you want the absolute path of a file then you can also use resolve function of path module
var somePath = "./img.jpg";
var resolvedPath = path.resolve(somePath);
console.log(resolvedPath);
/Users/vikasbansal/Desktop/temp/img.jpg