Convert Date from one format to another format in JavaScript

Question

I have a string of a date in javascript in format #1. I need to convert it to format #2.

The problem starts when one format is "dd/mm/yy" and the other is "mm/dd/yy".

The formats change dynamically and I have the formats as strings, but I need a function like

   Date newDate = convert(currentDate, currentFormatString, newFormatString).

How can I do it?

score 27 · Accepted Answer · edited Jun 20 '20 at 09:12

27

You should look into momentjs, which is a javascript date/time library. With that, you can easily convert between dates of different format. In your case, it would be:

string newDate = moment(currentDate, currentFormatString).format(newFormatString)

For example, moment("21/10/14", "DD/MM/YY").format("MM/DD/YY") would return "10/21/14"

edited Jun 20 '20 at 09:12

Community

1
1

answered Oct 22 '14 at 05:21

trekforever

3,914
25
29

var newDate = moment("Nov/21/2015", "mmm/DD/YYYY").format("MM/DD/YYYY");alert(newDate); -- This does not work. – user3115056 Nov 12 '15 at 17:21
1

^ `mmm/DD/YYYY` is not a valid format, you're looking for: `var newDate = moment("Nov/21/2015", "MMM/DD/YYYY").format("MM/DD/YYYY");alert(newDate);` – trekforever Nov 12 '15 at 18:09

score 2 · Answer 2 · edited Jun 27 '17 at 11:11

You can use the above described answer of momnet.js or the function below for splitting and using it

For using moment.js make sure you enter your old and new format in upper case

function parseDate(strDate) {

    var dateFormat = $('#currentDateFormat').val();

    var str;
    var res;

    var strFormat = dateFormat.split('.');
    if (strFormat.length != 3)
        strFormat = dateFormat.split('/');
    if (strFormat.length != 3)
        strFormat = dateFormat.split('-');

    str = strDate.split('.');
    if (str.length != 3)
        str = strDate.split('/');
    if (str.length != 3)
        str = strDate.split('-');


    if (strFormat[0].substr(0, 1) == 'd' && strFormat[1].substr(0, 1) == 'M' &&             
        strFormat[2].substr(0, 1) == 'y') // for dd MM yyyy
        res = new Date(str[2], str[1], str[0]);

    if (strFormat[0].substr(0, 1) == 'M' && strFormat[1].substr(0, 1) == 'd' &&
        strFormat[2].substr(0, 1) == 'y') // for MM dd yyyy
        res = new Date(str[2], str[0], str[1]);

    if (strFormat[0].substr(0, 1) == 'y' && strFormat[1].substr(0, 1) == 'M' &&
        strFormat[2].substr(0, 1) == 'd')
        res = new Date(str[0], str[1], str[2]);

    if (strFormat[0].substr(0, 1) == 'y' && strFormat[1].substr(0, 1) == 'd' &&         
        strFormat[2].substr(0, 1) == 'M')
        res = new Date(str[0], str[2], str[1]);

    return res;
}

score 1 · Answer 3 · answered Apr 14 '20 at 15:00

You can use the function below

console.log(changeDateFormat('12/1/2020','dd/MM/yyyy','MM/dd/yyyy'));

function changeDateFormat(value, inputFormat, outputFormat) {

let outputSplitter = "/";
let strOutputFormat = outputFormat.split(outputSplitter).map(i => i.toUpperCase());
if (strOutputFormat.length != 3) {
  strOutputFormat = outputFormat.split('-');
  outputSplitter = '-';
}

if (strOutputFormat.length != 3) throw new Error('wrong output format splitter :(');

let date = null;

if (value instanceof Date) {
  date = {
    ["YYYY"]: value.getUTCFullYear(),
    ["MM"]: value.getMonth() + 1,
    ["DD"]: value.getDate()
  }
}

if (typeof value == 'string') {
  let inputSplitter = "/";

  var strInputFormat = inputFormat.split(inputSplitter).map(i => i.toUpperCase());
  if (strInputFormat.length != 3) {
    strInputFormat = inputFormat.split('-');
    inputSplitter = '-';
  }

  if (strInputFormat.length != 3) throw new Error('wrong input format splitter :(');

  let dateElements = value.split(inputSplitter);
  if (dateElements.length != 3) throw new Error('wrong value :(');

  date = {
    [strInputFormat[0]]: dateElements[0],
    [strInputFormat[1]]: dateElements[1],
    [strInputFormat[2]]: dateElements[2],
  }
}

if (!date) throw new Error('unsupported value type:(');

let result = date[strOutputFormat[0]] + outputSplitter
  + date[strOutputFormat[1]] + outputSplitter 
  + date[strOutputFormat[2]];

return result;
 }

score 0 · Answer 4 · answered Oct 22 '14 at 05:20

0

It seems that you should use the library of query-dateformat git hub for jquery-dateformat
or you can use the normal function like date-time-formate, use the library to config the formate template

answered Oct 22 '14 at 05:20

Feng Lin

670
4
8

I can't understand how to use jquery-dateformat for what I need. How does the convert function knows what's the current format? – TamarG Oct 22 '14 at 05:37
JavaScript/or any third party lib cant know the format of your date string unless you specify it(if third party support so). It will assume it is in "mm/dd" format i.e month appears before day. – Amitesh Oct 22 '14 at 05:50
So it does not answer my problem. I need a function that I can set the current format. – TamarG Oct 22 '14 at 06:23

Convert Date from one format to another format in JavaScript

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