Javascript parsing Times without Date

Unfortunately, there's not a great solution. JavaScript only has a Date object, which is probably misnamed since it is really a date+time.

One thing you might want to think about deeper - you say you want to work with only time, but do you mean a time-of-day or do you mean a duration of time? These are two related, but slightly different concepts.

For example, you said you might want an operation like "15:00 + 1 hour". Well that would clearly be 16:00 either way. But what about "15:00 + 10 hours"? It would be 25:00 if you are talking about a duration, but it might be 01:00 if you are talking about time-of-day.

Actually, it might not be 01:00, since not all days have 24 hours in them. Some days have 23, 23.5, 24.5, or 25 hours, depending on what time zone and whether DST is starting or stopping on that day. So in the time-of-day context, you probably do want to include a particular date and zone in your calculation. Of course, if you are talking about straight 24-hours days, then this point is irrelevant.

If you are talking about durations - you might want to look again at moment.js, but not at the moment object. There is another object there, moment.duration. The reference is here.

And finally, you might want to consider just using plain javascript to parse out hours and minutes from the time string as numbers. Manipulate the numbers as necessary, and then output a string again. But your question seems like you're looking for something more managed.

Here's a moment.js solution for 12 or 24 hour times:

moment('7:00 am', ['h:m a', 'H:m']); // Wed Dec 30 2015 07:00:00 GMT-0600 (CST)
moment('17:00', ['h:m a', 'H:m']);   // Wed Dec 30 2015 17:00:00 GMT-0600 (CST)
moment('17:00 am', ['h:m a', 'H:m']);// Wed Dec 30 2015 17:00:00 GMT-0600 (CST)
moment('17:00 pm', ['h:m a', 'H:m']);// Wed Dec 30 2015 17:00:00 GMT-0600 (CST)

http://momentjs.com/docs/#/parsing/string-formats/