Convert string YYMMDD to YYYYMMDD in JavaScript

Question

I am just wondering is it possible to convert a date string YYMMDD to YYYY-MM-DD, in example 990102 -> 1999-01-02 in JavaScript?

EDIT from a comment :

If date 200102 is provided it need to output 2012-01-02, not 1920-01-02

Answer 1

You cannot unless you provide a condition on when to use 2000+ and when to use 1900+. Its basically less information in YY where the thousands and hundreds are missing. There is no obvious way to determine if 14 is 2014 or 1914

So you can take a window like [1990 - 2089]. So if YY>=90 use 1900+. If YY<90 use 2000+ The window can be adjusted per your requirement

I am not sure if there is any standard on what window to use.

@Kos says:

There's a POSIX standard: "When a century is not otherwise specified, values in the range [69,99] shall refer to years 1969 to 1999 inclusive, and values in the range [00,68] shall refer to years 2000 to 2068 inclusive"

@RobG says

ECMA-262 (which is probably more appropriate for javascript) says that any year from 0 to 99 should be treated as 1900 to 1999 (§20.3.2.1). But of course implementations can do what they want for formats not covered by the spec. In Safari, 1/1/49 is 2049, 1/1/50 is 1950.

//990102 -> 1999-01-02
//using window [1990-2089]
function convertDate(yymmdd) {
  var d = yymmdd; // YYMMDD
  var yy = d.substr(0, 2);
  var mm = d.substr(2, 2);
  var dd = d.substr(4, 2);
  var yyyy = (+yy < 90) ? '20' + yy : '19' + yy;
  return yyyy + '-' + mm + '-' + dd;
}
console.log(convertDate('900102'))
console.log(convertDate('140102'))
console.log(convertDate('890102'))

Answer 2

You can use substring method.

var date="990102";
console.log("19"+date.substring(0,2)+"-"+date.substring(2,4)+"-"+date.substring(4,6));