Q sample - deffered

gistfile1.txt

var Q = require('q');

function function_name(argument) {

	var deferred = Q.defer();

    if (err) {
        deferred.reject(err);
    } else {
        deferred.resolve(imageLocation(id, type, 'thumb'));
    }

	return deferred.promise;

}

// Call fb
function_name(argument)
	.then(function (result) {

	    return res.json(result);

	})
	.catch(function (error) {

	    var errString = error.message || error || '';
	    errString = errString.substr(0, 15);

	    return res.badRequest({
	        status: 'error',
	        err: errString
	    });

	});