How to tell if string time-A is before time-B?

Question

if I have 4 variables

startTime; endTime; startMerid; endMerid;

startMarid and endMarid are either going to be 'AM' or 'PM'.

but startTime and endTime are going to be strings like 'dd:dd'

so it may be start:12:30 PM and end:5:30 PM

How can I validate that the end time is not before the start time?

Thanks!!

Answer 1

You can use DateJS:

Date.parse('12:30pm') < Date.parse('5:30pm'); // true

EDIT:

Justin has a good point below. You can find the latest en-US version here

You can find the others in /trunk/build

Answer 2

Parse out the hours and minutes fields so you have two separate variables. Then add 12 to hours if it is PM, unless the hour value is already 12. You can then compare the values directly:

if (startTimeHrs * 60 + startTimeMins) > 
   (  endTimeHrs * 60 + endTimeMins){ ... }