算法建议：如何查找最新日期（javascript）

Question

I am trying to add a function to my website that sorts through dates in formats like this "Apr 5, 2016, 5:56 PM" and figuring out if it is more recent than this "Apr 5, 2016, 9:56 AM" and by how long in (hours say). I know it would have to do with figuring out the month, then the year, then the hour and comparing them. Does anyone have any advice/samples on how to do this in javascript? it is really bugging me?

Thanks

Answer 1

You should always manually parse date strings, do not use Date.parse or the Date constructor (which are equivalent for parsing). A library can help, but if you only have a single format, a bespoke function can do the job, eg

 // Apr 5, 2016, 5:56 PM function parseDateString(s) { var months = {jan:0,feb:1,mar:2,apr:3,may:4,jun:5, jul:6,aug:7,sep:8,oct:9,nov:10,dec:11}; var b = s.match(/\\w+/g); var h = b[3]%12 + (/am/i.test(s)? 0 : 12); return new Date(b[2], months[b[0].toLowerCase()], b[1], h, b[4]); } var s = 'Apr 5, 2016, 5:56 PM'; document.write(parseDateString(s)); 

If you need a more general parser, there is moment.js but it may be way more than you need. If you just need a small parser and formatter, consider a utility like date-format.js or similar.

Answer 2

I think this might help you out:

var date1 = new Date("7/13/2010");
var date2 = new Date("12/15/2010");
var timeDiff = Math.abs(date2.getTime() - date1.getTime());
var diffDays = Math.ceil(timeDiff / (1000 * 3600 * 24));