When you need to get file stats using NodeJS (which calls the unix stat command in the background), you can use the fs.stat call as shown below:

fs.stat('path/to/file', function (err, stats) {
});

The stats object returned here is an instance of fs.Stats which contains a mode property. You can use this property to determine the unix file permissions for the file path provided. The only problem is that this mode property just gives you a number (as referenced in this GitHub issue). To view the permissions in the standard unix octal format (e.g. 0445, 0777 etc) you can use the following code:

var unixFilePermissions = '0' + (stats.mode & parseInt('777', 8)).toString(8);

Some examples of the mode before and after calling the above snippet:

33188 -> 0644
33261 -> 0755