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I was having some problem to sort the date followed by time in descending order using JavaScript. Here is some inputs:

[{chatroomID: "1", date: "12/26/2017", time: "10:31:32 PM"},
{chatroomID: "2", date: "12/26/2017", time: "10:38:01 PM"},
{chatroomID: "3", date: "12/26/2017", time: "10:35:14 PM"}]

I wanted to sort them in descending order whereby the latest one will be on top but I not sure how to do it.

The desired output:

[{chatroomID: "2", date: "12/26/2017", time: "10:38:01 PM"},
{chatroomID: "3", date: "12/26/2017", time: "10:35:14 PM"},
{chatroomID: "1", date: "12/26/2017", time: "10:31:32 PM"}]

If the result comes from the same date, then I will sort according to time. Otherwise, the latest date will be on top. Any ideas?

Thanks!

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1 Answer 1

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Just concat the date and time, then parse it to a Date and get the timestamp. From then on, it's just plain old sorting.

const datetimes = [
  {chatroomID: "1", date: "12/26/2017", time: "10:31:32 PM"},
  {chatroomID: "2", date: "12/26/2017", time: "10:38:01 PM"},
  {chatroomID: "3", date: "12/26/2017", time: "10:35:14 PM"}
]

const sorted = datetimes.sort((a, b) => {
  const aDate = new Date(a.date + ' ' + a.time)
  const bDate = new Date(b.date + ' ' + b.time)
  
  return bDate.getTime() - aDate.getTime()
})

console.log(sorted)

Update: The linked answer in the comment by Marcel Gwerder indicates you could just skip getTime() altogether and just compare the Dates.

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2 Comments

I think using new Date or Date.parse with a string sill isn't a really safe thing to do, see the note on MDN.
@MarcelGwerder Fair point - I doubt browsers will be inconsistent with the OP's formats - but I wouldn't swear on this.