isExecutable
‘isExecutable(string)’ (BOOL)
This will return true if the file path is executable, otherwise it will return false.
This wikipedia article explains permissions on Unix-like systems.
Examples
var fs = require('fs');
var path = '/Full/Path/To/exec';
if (fs.isExecutable(path))
console.log('"'+path+'" is executable.');
else
console.log('"'+path+'" is NOT executable.');
phantom.exit();