date string formatting

Question

The best way to take a string that is formated like...

YYYY-MM-DD

and make it appear like...

MM/DD/YYYY

The reason it is not a javascript date object is because I am working with massive amounts of data and these dates are being pulled from a database.

I see no need to convert it to a date object.

probably a duplicate in some capacity or another... couldn't find anything upon first search — Derek Adair
– Derek Adair, Commented Feb 3, 2010 at 18:21
This is best solved with datetime parsing and formatting, not string manipulation as the tag suggests. — Mark Byers
– Mark Byers, Commented Feb 3, 2010 at 18:22

Guffa · Accepted Answer · 2010-02-03 18:24:27Z

4

How about:

s.substr(5,2) + '/' + s.substr(8) + '/' + s.substr(0,4)

answered Feb 3, 2010 at 18:24

Guffa

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1 Comment

Guffa Over a year ago

@cjstehno: I also swapped the day and month, but it's fixed now. :)

Vivin Paliath · Accepted Answer · 2010-02-03 18:27:02Z

You can use a regular expression in JavaScript (assuming JS because your question is tagged as such):

var date = "2010-05-09"; var formatted = date.replace(/([0-9]{4})-([0-9]{2})-([0-9]{2})/, "$2/$3/$1")

What I like about this more than using substring is that it seems more apparent what is being done.

tvanfosson · Accepted Answer · 2010-02-03 19:59:52Z

1

If you replace the dashes with slashes it will parse, then you can use the date functions to get the various components (or convert to string using one of the various toString() functions).

var date = new Date( Date.parse( old.replace(/-/g,'/') ) ); alert( date.getMonth() + '/' + date.getDate() + '/' + date.getFullYear() );

This has the advantage of being able to use the date as a date for calculations, not merely doing string formatting. If string formatting is all you need AND your date strings are always valid, then using @Guffa's substr method is probably the best way to handle it.

edited Feb 3, 2010 at 19:59

answered Feb 3, 2010 at 18:30

tvanfosson

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6 Comments

Derek Adair Over a year ago

The dates have no functionality and are always valid (they are inserted as a timestamp via mysql)... so at least I hope mysql's datestamp format would be valid!! lol

ghoppe Over a year ago

Actually, in my testing, vivin's regular expression method is ~20% faster. The slowest method is cjstehno's split into array and combine method.

tvanfosson Over a year ago

@ghoppe -- ok, but I would submit to you that "faster" is not always equivalent to "better". Readability is also a concern. Depending on your regular expression foo, the regex solution may simply be incomprehensible whereas anyone ought to be able to figure out substr. I actually find mine to be the most comprehensible even though it's probably the slowest. Anyone who can't see immediately what it's doing ought not be programming. :-)

tvanfosson Over a year ago

I fixed some issues with parse() returning ms, not an actual Date. The replacement (unlike C#) needs to use a regex and specify global replacement. The solution as it stands now has been tested.

ghoppe Over a year ago

It's still not exactly what Derek wants as getMonth() and getDate() returns a single digit when <10.

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cjstehno · Accepted Answer · 2010-02-03 21:24:51Z

1

By brute force you could do something like:

var old = '2010-02-03'.split('-'); var desired = old[1] + '/' + old[2] + '/' + old[0];

Saves the hassle of working with Date object.

edited Feb 3, 2010 at 21:24

answered Feb 3, 2010 at 18:25

cjstehno

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1 Comment

ghoppe Over a year ago

Not to be overly pedantic, but this will not work. new is a reserved word in Javascript. You'll have to use a different variable name.

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