JavaScript AM/PM time comparison

Question

Suppose I have 2 datetime variables:

var fromdt = "2013/05/29 12:30 PM";
var todt = "2013/05/29 01:30 AM";

I want to compare these 2 datetimes. How can I get Javascript to recognize whether the time is AM or PM?

I think Javascript will compare the time in 24 hours format. Do I need to convert the time to 24 hour format? Is that correct? Could someone please suggest the correct solution....

The usual way to deal with dates is having them in 24 hour format where `01:30` = AM and `13:30` = PM. With the times you provide, there is no way to tell whether they are AM or PM. — Pekka, Jun 02 '13 at 07:24
So how would **YOU** recognize if `01:30` is a daytime or night time? — zerkms, Jun 02 '13 at 07:24
@zerkms..I think Javascript will compare the time by 24 hours format. And we need to convert the time to 24 hours format? — Dylan, Jun 02 '13 at 07:26
@Dylan: I didn't ask about JS, I asked about you. Btw, `AM/PM` format is just a time representation, how it stores internally - is another question. But for sake of simplicity - internal data doesn't care of am/pm at all — zerkms, Jun 02 '13 at 07:27
So the strings do have "AM" or "PM" in them? You didn't think that was relevant information? — JJJ, Jun 02 '13 at 07:28
@zerkms: Yes, I've edited my code and set AM and PM to the datestrings.. — Dylan, Jun 02 '13 at 07:28

score 8 · Accepted Answer · edited Apr 19 '21 at 08:02

8

Just use straight javascript functions

var fromdt = "2013/05/29 12:30 PM";
var todt = "2013/05/29 01:30 AM";
var from = new Date(Date.parse(fromdt));
var to = new Date(Date.parse(todt));

alert(from);
alert(to)

if (from > to) alert("From");
else alert("To");

Once the date is parsed into date form, you can do what you like with it. And you can compare dates using the standard operator signs ( >, < etc)

I'm not sure what you need to do with them, but http://www.w3schools.com/jsref/jsref_obj_date.asp is an okay reference.

And heres a crappy sandbox with the above code http://jsfiddle.net/QpFcW/

and a better one that XX deleted :( http://jsfiddle.net/QpFcW/1/

edited Apr 19 '21 at 08:02

Manas Khandelwal

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answered Jun 02 '13 at 07:43

monkeyhouse

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will datDate.parse(fromdt) recognize AM/PM from Datestring? – Dylan Jun 02 '13 at 07:53
when it parses the string into the date object, it implicitly recognizes the am/pm feature as part of the date – monkeyhouse Jun 02 '13 at 08:01

score 0 · Answer 2 · edited Apr 19 '21 at 08:03

Use this function

function get_time() {
  var time_t = "";
  var d = new Date();
  var cur_hour = d.getHours();

  cur_hour < 12 ? (time_t = "am") : (time_t = "pm");
  cur_hour == 0 ? (cur_hour = 12) : (cur_hour = cur_hour);
  cur_hour > 12 ? (cur_hour = cur_hour - 12) : (cur_hour = cur_hour);
  var curr_min = d.getMinutes().toString();
  var curr_sec = d.getSeconds().toString();
  if (curr_min.length == 1) {
    curr_min = "0" + curr_min;
  }
  if (curr_sec.length == 1) {
    curr_sec = "0" + curr_sec;
  }
  $("#updatedTime").html(
    cur_hour + ":" + curr_min + ":" + curr_sec + " " + time_t
  );
  alert(cur_hour + ":" + curr_min + ":" + curr_sec + " " + time_t);
}

JavaScript AM/PM time comparison

2 Answers2