MomentJS getting JavaScript Date in UTC

Question

I am not able to get the JavaScript Date string for MongoDB record via the following  It keeps using my local time   var utc   moment utc   valueOf    console log moment utc utc  toDate       Output   Tue Nov 11 2014 14 42 51 GMT-0500  EST    I need it to be in UTC  so I can stick this timestamp in Mongo so type would be Date   How can I do that

User · Answer

Calling toDate will create a copy  the documentation is down-right wrong about it not being a copy   of the underlying JS Date object  JS Date object is stored in UTC and will always print to eastern time  Without getting into whether  utc   modifies the underlying object that moment wraps use the code below   You don t need moment for this   new Date   getTime     This works  because JS Date at its core is in UTC from the Unix Epoch  It s extraordinarily confusing and I believe a big flaw in the interface to mix local and UTC times like this with no descriptions in the methods

User · Answer

A timestamp is a point in time  Typically this can be represented by a number of milliseconds past an epoc  the Unix Epoc of Jan 1 1970 12AM UTC   The format of that point in time depends on the time zone  While it is the same point in time  the  hours value  is not the same among time zones and one must take into account the offset from the UTC    Here s some code to illustrate  A point is time is captured in three different ways    var moment   require   moment      var localDate   new Date    var localMoment   moment    var utcMoment   moment utc    var utcDate   new Date  utcMoment format         These are all the same console log   localData unix       localDate valueOf      console log   localMoment unix       localMoment valueOf      console log   utcMoment unix       utcMoment valueOf         These formats are different console log   localDate       localDate    console log   localMoment string       localMoment format      console log   utcMoment string       utcMoment format      console log   utcDate        utcDate       One to show conversion console log   localDate as UTC format       moment utc  localDate   format      console log   localDate as UTC unix       moment utc  localDate   valueOf        Which outputs this   localData unix   1415806206570 localMoment unix   1415806206570 utcMoment unix   1415806206570 localDate   Wed Nov 12 2014 10 30 06 GMT-0500  EST  localMoment string   2014-11-12T10 30 06-05 00 utcMoment string   2014-11-12T15 30 06 00 00 utcDate    Wed Nov 12 2014 10 30 06 GMT-0500  EST  localDate as UTC format   2014-11-12T15 30 06 00 00 localDate as UTC unix   1415806206570   In terms of milliseconds  each are the same  It is the exact same point in time  though in some runs  the later millisecond is one higher    As far as format  each can be represented in a particular timezone  And the formatting of that timezone d string looks different  for the exact same point in time   Are you going to compare these time values  Just convert to milliseconds  One value of milliseconds is always less than  equal to or greater than another millisecond value   Do you want to compare specific  hour  or  day  values and worried they  came from  different timezones  Convert to UTC first using moment utc  existingDate    and then do operations  Examples of those conversions  when coming out of the DB  are the last console log calls in the example

User · Answer

Or simply   Date now  From MDN documentation      The Date now   method returns the number of milliseconds elapsed since January 1  1970   Available since ECMAScript 5 1  It s the same as was mentioned above  new Date   getTime     but more shortcutted version

[node.js] MomentJS getting JavaScript Date in UTC

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