Converting string date for new date constructor

Question

I have a string date with the format YYYYMMDD (20170603). There are no hyphens in this string, it is just one string. I want to convert this string so it can be used by a date constructor. I want to do the following new Date(2017,06,03) What is the most efficient way of doing this? Note: I want my date to be in YYYY MM DD format

@SurabhilSergy No this is not like that question because I'd like my string to be exactly the way it is in date format — Bytes, Jul 23 '17 at 17:45
4 answers, all but 1 wrong. The equivalent of "20170603" is `new Date('2017', '06' - 1, '03')`. This is a duplicate of many other questions. — RobG, Jul 23 '17 at 22:41

dev8080 · Accepted Answer · 2017-07-25T05:45:38.390

1

You could just use substring():

new Date( parseInt( str.substring(0,4) ) , 
          parseInt( str.substring(4,6) ) -1 , 
          parseInt( str.substring(6,8) ) 
        );

Like the comments show, you could well leave out the parseInt:

new Date( str.substring(0,4) , 
          str.substring(4,6) - 1 , 
          str.substring(6,8) 
        );

edited Jul 25 '17 at 05:45

answered Jul 23 '17 at 17:47

dev8080

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The month needs to be -1 and *parseInt* is redundant. This is a duplicate of many other questions. – RobG Jul 23 '17 at 22:40
@RobG You're right. To do the month though, you would need the parseInt. – dev8080 Jul 24 '17 at 05:47
There is no need for parseInt. The `-` operator coerces the arguments to number, so `"5" - 1` returns `4` (as does `var n = "5"; --n`). – RobG Jul 24 '17 at 22:44
@RobG You're right. I didn't know you could do that. – dev8080 Jul 25 '17 at 05:44

guest271314 · Answer 2 · 2017-07-23T22:44:30.977

0

You can use String.prototype.slice()

let month = +str.slice(4, 6);
let date = new Date(str.slice(0, 4), !month ? month : month -1, str.slice(6))

edited Jul 23 '17 at 22:44

answered Jul 23 '17 at 17:47

guest271314

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@RobG Good point. See updated post – guest271314 Jul 23 '17 at 22:42

score 0 · Answer 3 · answered Jul 23 '17 at 17:48

0

var dateStr = "20170603";
var match = dateStr.match(/(\d{4})(\d{2})(\d{2})/);
var date = new Date(match[1] + ',' + match[2] + ',' + match[3])

console.log(date);

answered Jul 23 '17 at 17:48

caramba

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The month should be -1 – RobG Jul 23 '17 at 22:41

Converting string date for new date constructor

3 Answers3