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I'm working on a Phonegap-based iOS app, which is already done for Android. The following lines are working fine for Android but not for iOS. Why?

var d = new Date("2015-12-31 00:00:00"); console.log(d.getDate() + '. ' + d.getMonth() + ' ' + d.getFullYear();

Result for Android:

31.11 2015

Result on iOS:

NaN. NaN NaN

Where is the difference coming from?

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8 Answers 8

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163

Your date string is not in a format specified to work with new Date. The only formats in the spec are a simplified version of ISO-8601 (added in ES5 in 2009 and updated in ES2015 and ES2016), and the format output by Date.prototype.toString. Your string isn't in either format, but it's really close to the ISO-8601-like format. It would also be easy to change it to a format that isn't in the spec, but is universally supported

Four options for you:

  • Use the upcoming Temporal feature (it's now at Stage 3)
  • The specified format
  • An unspecified format that's near-universally supported
  • Parse it yourself

Use the upcoming Temporal feature

The Temporal proposal is at Stage 3 as of this update in August 2021. You can use it to parse your string, either treating it as UTC or as local time:

Treating the string as UTC:

// (Getting the polyfill) const {Temporal} = temporal; const dateString = "2015-12-31 00:00:00"; const instant = Temporal.Instant.from(dateString.replace(" ", "T") + "Z"); // Either use the Temporal.Instant directly: console.log(instant.toLocaleString()); // ...or get a Date object: const dt = new Date(instant.epochMilliseconds); console.log(dt.toString());
<script src="https://unpkg.com/@js-temporal/polyfill/dist/index.umd.js"></script>

Or treating it as local time:

// (Getting the polyfill) const {Temporal} = temporal; const dateString = "2015-12-31 00:00:00"; console.log("Parsing as local time:"); const tz = Temporal.Now.timeZone(); const instant = tz.getInstantFor(dateString.replace(" ", "T")); console.log(instant.toLocaleString()); const dt = new Date(instant.epochMilliseconds); console.log(dt.toString());
<script src="https://unpkg.com/@js-temporal/polyfill/dist/index.umd.js"></script>

Temporal doesn't have the problem mentioned below that the specified date/time string format historically had when no timezone was specified.

The ISO-8601-like format

If you change the space to a T, you'll be in spec:

var dateString = "2015-12-31 00:00:00"; // Treats the string as local time -- BUT READ BELOW, this varied var d = new Date(dateString.replace(" ", "T")); console.log(d.toString());

(I'm assuming you're not actually using a string literal, hence the replace call.)

For reliable timezone handling in old browsers, you'll also want to append a Z (for GMT/UTC) or a timezone indicator (+/- HH:MM), because the handling of strings without them was mis-specified in ES5, updated in ES2015, and then updated further in ES2016. Current versions of modern browsers follow the spec now, which says:

  • If there's a time on the string but and no timezone indicator, parse the string in local time
  • If there's no time on the string and no timezone indicator, parse the string in UTC

(ES5 said always default to UTC. ES2015 said always default to local time. ES2016 is where the current behavior was defined. It's been stable since.)

So it's best to include a timezone indicator, especially if you have to support older browsers. Note that it must be a Z (UTC) or +/- HH:MM; abbreviations like CST are not allowed, as there's no standard for them. Here's a UTC example:

var dateString = "2015-12-31 00:00:00"; // Treat the string as UTC var d = new Date(dateString.replace(" ", "T") + "Z"); console.log(d.toString());

An unspecified format that's near-universally supported

There's a seconnd format that isn't in the specification but is near-universally supported and has been for a long time: YYYY/MM/DD HH:MM:SS, which is interpreted as local time. So:

var dateString = "2015-12-31 00:00:00"; // Treats the string as local time var d = new Date(dateString.replace(/-/g, "/")); console.log(d.toString());

Again, though, that's unspecified behavior, so caveat emptor. But it works in at least IE8+ (probably earlier), Chrome and anything else using the V8 JavaScript engine, Firefox, and Safari.

Parse it yourself

It's also easy to parse that string yourself. Using ES2020+ features:

function parseDate(str) { const [dateparts, timeparts] = str.split(" "); const [year, month, day] = dateparts.split("-"); const [hours = 0, minutes = 0, seconds = 0] = timeparts?.split(":") ?? []; // Treats the string as UTC, but you can remove the `Date.UTC` part and use // `new Date` directly to treat the string as local time return new Date(Date.UTC(+year, +month - 1, +day, +hours, +minutes, +seconds)); } const dateString = "2015-12-31 00:00:00"; const d = parseDate(dateString); console.log(d.toString());

Or with only ES5-level features (since the question is from 2015):

function parseDate(str) { var parts = str.split(" "); var dateparts = parts[0].split("-"); var timeparts = (parts[1] || "").split(":"); var year = +dateparts[0]; var month = +dateparts[1]; var day = +dateparts[2]; var hours = timeparts[0] ? +timeparts[0] : 0; var minutes = timeparts[1] ? +timeparts[1] : 0; var seconds = timeparts[2] ? +timeparts[2] : 0; // Treats the string as UTC, but you can remove the `Date.UTC` part and use // `new Date` directly to treat the string as local time return new Date(Date.UTC(year, month - 1, day, hours, minutes, seconds)); } var dateString = "2015-12-31 00:00:00"; var d = parseDate(dateString); console.log(d.toString());

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9 Comments

@NULL: I've never seen a JavaScript engine that didn't support it. IE6 and up do, every version of Firefox I've ever seen, every version of Chrome, every version of Opera. But, one must always test on ones target environments (whether something is "standard" or not, sadly).
In my own testing I found that the YYYY/MM/DD HH:MM:SS solution gives the same date on iOS as I was hoping to get from YYYY-MM-DD HH:MM:SS, whereas the solution replacing the space with a T adjusted my date by the timezone amount .. (adding on 10 hours to the time). (Summary: YYYY/MM/DD HH:MM:SS works, YYYY-MM-DDTHH:MM:SS gets adjusted for timezone and for some situations that will be wrong)
@user1290746: Probably the Z error in the specification, I've added a note about it above.
@user1290746 thats because adding T converts it to universal time format. the other solution is better replacing '-' with '/'
@T.J.Crowder - It's 2020, and the solution still applicable with my project :). Had to deal with date stored in "2015-05-30 00:00:00" format, and JavaScript in iOs (I am assuming its running off Safari) still churned out the NaN. Great solution!
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I can't tell you why. Maybe because iOS doesn't support the Javascript Date function as well as Android, or support a different format?

But I can give you a workaround:

var s = "2015-12-31 00:00:00".split(" ")[0].split("-"), d = new Date( s[0], s[1], s[2], 0, 0, 0 ); console.log(d); 
var s = "2015-12-31 00:00:00".replace(/[ :]/g, "-").split("-"), d = new Date( s[0], s[1], s[2], s[3], s[4], s[5] ); console.log(d);
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2 Comments

I will try it and get back to you
This is a valid solution. Works on both iOS and the rest. However, for some reason if you have a date that consits of 2019 2 1 The date goes backwords by a month for some reason. var s = d.replace(/[ :]/g, "-").split("-") console.log(new Date(s[0], s[1] - 1, s[2]));
6

A solution that works for both IOS and Android, and avoid string manipulation when it isn't required is

let fullDate = "1991-03-29 00:00:00"; let date = new Date(fullDate); // In case its IOS, parse the fulldate parts and re-create the date object. if(Number.isNaN(date.getMonth())) { let arr = fullDate.split(/[- :]/); date = new Date(arr[0], arr[1]-1, arr[2], arr[3], arr[4], arr[5]); }
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If anybody is still looking for it.

works for me in IE, Safari, IOS-FF, IOS-Safari ... etc.

getIOSSaveDateObj = function(dateString){ if(dateString.indexOf('-') > 0){ var arr = dateString.split(/[- :]/); var date = new Date(arr[0], arr[1]-1, arr[2], arr[3], arr[4], arr[5]); }else{ var arr = dateString.split(/[. :]/); var date = new Date(arr[2], arr[1]-1, arr[0], arr[3], arr[4], arr[5]); } return date; }
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0

I had such a hard time trying to solve this, i finally went for an easier solution and used moment.js. Not much you need to do just declare the dates and works in every device.

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I was using date format 2024-05-02 and it was not working later I change the format to 05/02/2024 and it worked

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This does not provide an answer to the question. Once you have sufficient reputation you will be able to comment on any post; instead, provide answers that don't require clarification from the asker. - From Review
-1

Try with var d = new Date("2015/12/31 00:00:00"); Works for me.

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1 Comment

This does not work on my iPhone MN4P2X/A with Safari. It needs the T inbetween the date and the time or it returns 'Invalid Date'
-3

Also 

var d = new Date("2015/12/31T00:00:00");

works for me :)

Thanks @dda

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4 Comments

Doesn't work for me without replacing the space with a T
This does not work on my iPhone MN4P2X/A with Safari. It needs the T inbetween the date and the time or it returns 'Invalid Date'
@NULLpointer it worked for me, maybe due to old version. Anyway, I edited my answer to your comments.
Correction to my comment above - your editted answer (with the T replacing the space) this works for me.

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