var timezone = "America/Los_Angeles";
var dt = 'Sept 21, 2018';
var m = moment.tz(dt, 'MMMM D, YYYY', timezone);
var converted = m.toDate().toString();
console.log(converted);
var x = moment.tz(converted, 'MMMM D, YYYY', timezone);
console.log(x.isValid());
//if parsing worked, use the new value
if (x.isValid()) {
console.log(x.toDate());
}
// if not, assume it's already the correct format and just use that
else
{
console.log(converted);
}