promisify basic non-async operations javascript

var existsAsync = function(path) {
 return new Promise(function(resolve, reject) {
 fs.exists(path, function(exists) {
 // exists is a boolean
 if (exists) {
 // Resolve successfully
 resolve();
 } else {
 // Reject with error
 reject(new Error('path does not exist'));
 }
 });
});
// Use as a promise now
existsAsync('/path/to/some/file').then(function() {
 console.log('file exists!');
}).catch(function(err) {
 // file does not exist
 console.error(err);
});