Using momentjs to convert date to epoch then back to date

Question

I m trying to convert a date string to epoch  then epoch back to the date string to verify that I m providing the correct date string   var epoch   moment  10 15 2014 9 00   unix       do I need to do  local    var momentDate   moment epoch      I ve also tried moment utc epoch   var momentDateStr   momentDate calendar    alert  Values are  epoch       epoch      momentDateStr       momentDateStr     Renders  Values are  epoch   1413378000  momentDateStr   01 17 1970   Note  I m using the following version of the moment js script    cdnjs cloudflare com ajax libs moment js 2 8 3 moment-with-locales js

User · Answer

http   momentjs com docs   displaying unix-timestamp   You get the number of unix seconds  not milliseconds   You you need to multiply it with 1000 or using valueOf   and don t forget to use a formatter  since you are using a non ISO 8601 format  And if you forget to pass the formatter  the date will be parsed in the UTC timezone or as an invalid date   moment  10 15 2014 9 00    MM DD YYYY HH mm   valueOf

User · Answer

There are a few things wrong here    First  terminology    Epoch  refers to the starting point of something   The  Unix Epoch  is Midnight  January 1st 1970 UTC   You can t convert an arbitrary  date string to epoch    You probably meant  Unix Time   which is often erroneously called  Epoch Time    unix   returns Unix Time in whole seconds  but the default moment constructor accepts a timestamp in milliseconds   You should instead use  valueOf   to return milliseconds   Note that calling  unix   1000 would also work  but it would result in a loss of precision  You re parsing a string without providing a format specifier   That isn t a good idea  as values like 1 2 2014 could be interpreted as either February 1st or as January 2nd  depending on the locale of where the code is running    This is also why you get the deprecation warning in the console    Instead  provide a format string that matches the expected input  such as   moment  10 15 2014 9 00    M D YYYY H mm     calendar   has a very specific use   If you are near to the date  it will return a value like  Today 9 00 AM    If that s not what you expected  you should use the  format   function instead   Again  you may want to pass a format specifier  To answer your questions in comments  No - you don t need to call  local   or  utc      Putting it all together   var ts   moment  10 15 2014 9 00    M D YYYY H mm   valueOf    var m   moment ts   var s   m format  M D YYYY H mm    alert  Values are  ts       ts      s       s     On my machine  in the US Pacific time zone  it results in      Values are  ts   1413388800000  s   10 15 2014 9 00   Since the input value is interpreted in terms of local time  you will get a different value for ts if you are in a different time zone   Also note that if you really do want to work with whole seconds  possibly losing precision   moment has methods for that as well   You would use  unix   to return the timestamp in whole seconds  and moment unix ts  to parse it back to a moment   var ts   moment  10 15 2014 9 00    M D YYYY H mm   unix    var m   moment unix ts

[javascript] Using momentjs to convert date to epoch then back to date

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