Calculate amount of time until the next hour

Question

I'm working on a busing website project and the buses run every hour. I'm having trouble creating a widget that finds the time between now and the next hour, so that it is clear when the next bus will run. My client requires that it is in javascript. Any suggestions? Thanks in advance.

Answer 1

To know exactly the miliseconds from now to the next hour:

function msToNextHour() {
    return 3600000 - new Date().getTime() % 3600000;
}

Please note that this will strictly tell you how many milliseconds until the NEXT hour (if you run this at 4:00:00.000 it will give you exactly one hour).

Answer 2

function getMinutesUntilNextHour() { return 60 - new Date().getMinutes(); }

Note that people who's system clocks are off will miss their bus. It might be better to use the server time instead of the time on the client's computer (AKA at least partly a non-client-side-javascript solution).