node trick

call_vim.js

const child_process = require('child_process');                                                      
const editor = process.env.EDITOR || 'vi';                                                           
                                                                                                     
const child = child_process.spawn(editor, ['/tmp/somefile.txt'], {                                   
    stdio: 'inherit'                                                                                 
});                                                                                                  
                                                                                                     
child.on('exit', function (e, code) {                                                                
    console.log("finished");                                                                         
}); 

get_root_dir.js

const path = require('path');

const root = require.main.filename;
const rootPath = path.dirname(root);

console.log(rootPath);