JavaScript Date / Time

Question

I have the following input and i can change the source of this data

Input

var strDate = "/Date(1391402871117+0100)/";

I can convert it to a date using eval, but i really dont want to eval

var DateResult1 = eval ("new Date(1391402871117+0100)");
console.log(DateResult1); // Date {Mon Feb 03 2014 05:47:51 GMT+0100 (Romance Standard Time)}

I did try this, sadly do not work:

// Remove /Date( )/
strDate = strDate.replace(/[^\d+]/g,'');

var DateResult3 = new Date(strDate);
console.log(DateResult3); //Date {Invalid Date}

When i write result of strDate i manual with out " it work.

var DateResult2 = new Date(1391402871117+0100);
console.log(DateResult2); // Date {Mon Feb 03 2014 05:47:51 GMT+0100 (Romance Standard Time)}

How can convert the input data into a date with out using eval or any library?

Very ugly solution new Date(+"/Date(1391402871117+0100)/".slice(6, -2).split("+").reduce(function (a, b) { return +a + +b; })); — Givi
– Givi, Commented Feb 3, 2014 at 12:22

lanzz · Accepted Answer · 2014-02-03 12:24:13Z

2

You are very likely not getting a correct result out of this code:

var DateResult2 = new Date(1391402871117+0100);

The problem is the addition: 1391402871117+0100. 0100 is an octal constant, equal to 64 in decimal, which would add 64 milliseconds to the 1391402871117 timestamp. It seems likely to be indended as a time zone instead, but the Date constructor does not support time zones — only UTC and the local time zone of the browser.

Since UNIX timestamps are actually absolute (they are always in UTC), using just the timestamp would result in a Date instance referencing the correct instant in time, but possibly at another time zone. You can disregard the +0100 part, by converting the "1391402871117+0100" into an integer using parseInt:

strDate = strDate.replace(/[^\d+]/g,'');
var DateResult2 = new Date(parseInt(strDate));

answered Feb 3, 2014 at 12:24

lanzz

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2 Comments

Givi Over a year ago

Maybe i'm wrong but 1391402871117+0100 is same as 1391402871117+100 so if you don't parse octal as decimal it simply removes first 0.

lanzz Over a year ago

The JS code itself is new Date(1391402871117+0100). You don't have to parse octal — the Javascript engine of the browser does, and it indeed does parse octal constants as octal. You can try it in the JS console: 0+0100 would give you 64, not 100 as it would if the 0100 was parsed as decimal 100.

Josh Harrison · Accepted Answer · 2014-02-04 20:55:40Z

If you can change the data source, as you say, why not do this?

Have your data source generate something like this, to add the timezone offset to the timestamp:

// convert timezone offset hours into seconds and add them to the timestamp
return (unixTimestamp + (timezoneOffsetHours * 3600));

Then you can do something like this in your JS:

// Math.floor works faster than parseInt to convert a string to integer :)
var timestamp = Math.floor(result of above timestamp generation);
var DateResult = new Date(timestamp);

The reason:

new Date() can't handle timezones specified in this way (or at all as far as I can Google)

Zaheer Ahmed · Accepted Answer · 2014-02-03 12:22:16Z

0

try by parsing string to int:

var strDate = "/Date(1391402871117+0100)/";
strDate = strDate.replace(/[^\d+]/g, '');
var DateResult3 = new Date(parseInt(strDate.split('+')[0]) + parseInt(strDate.split('+')[1]));
console.log(DateResult3);

Here is Demo

answered Feb 3, 2014 at 12:22

Zaheer Ahmed

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