将UTC时间转换为yyyymmdd格式的Javascript

Question

I'm trying to convert a date object to UTC and then convert it to yyyymmdd format. Here is my code

 var scheduleDate = '2016/10/29 17:00'; var d = new Date(scheduleDate); var utcdate = d.toUTCString(); var mm = utcdate.getUTCMonth() + 1; var dd = utcdate.getUTCDate(); alert( [date.getUTCFullYear(), !mm[1] && '0', mm, !dd[1] && '0', dd].join('')); 

But I'm getting the below error:

utcdate.getUTCMonth is not a function

How can i get the month and date from a UTC string date format ?

Answer 1

Your variable utcdate is a string and so it does not have getUTCMonth or getUTCDate methods.

Further down you call the getUTCFullYear method on a variable that is not defined: date .

Finally, the way you try to pad with zeroes will not work, as mm and dd are not strings, and so when you index them with [1] , JavaScript will coerce these numbers to Number objects, but they don't have a 1 property, even when they have two digits. So you'll always get the padded 0 on top of that.

If you would fix that by first coercing those numbers to strings, it still would not work, as the && operator will yield false in some cases, which will be output as such: false .

Long story short, there are easier ways to get the UTC yyyymmdd format of a date. For example by extracting it from the left side of the yyyy-mm-ddThh:nn:ss..... format that toISOString returns:

 var d = new Date('2016/10/29 17:00'); console.log(d.toISOString().replace(/-|T.*/g,'')); 

Be aware that the UTC date is at some moments in time one day off compared to the date in the local time zone. If you need to prevent that, then I would suggest using toLocaleDateString with a locale that has a big-endian date format standard , such as Sweden, Lithuania, Hungary, South Korea, ...:

date.toLocaleDateString('se')

To remove the delimiters ( - ) is just a matter of replacing the non-digits:

 var d = new Date('2016/10/29 17:00'); console.log(d.toLocaleDateString('se').replace(/\\D/g, '')); 

Answer 2

If the known date is for UTC time zone, you can create the date object using the Date.UTC() method, then you can display the date local to the client (browser) time zone like so:

 //var scheduleDate = '2016/10/29 17:00'; // If known date is in UTC, create the date object like so: var d = new Date(Date.UTC(2016,(10 - 1),29,17,0)); // UTC version of the date var mmUTC = d.getUTCMonth() + 1; var ddUTC = d.getUTCDate(); var hhUTC = d.getUTCHours(); // local to the browser (client) time zone var mm = d.getMonth() + 1; var dd = d.getDate(); var hh = d.getHours(); // display values console.log('UTC values: hour:['+ hhUTC +'] month:['+ mmUTC +'] day:['+ ddUTC +']'); console.log('Client Time: hour:['+ hh +'] month:['+ mm +'] day:['+ dd +']'); console.log('Client yyyymmdd:['+ d.getFullYear() + ((mm < 10) ? '0'+ mm : mm) + dd +']');