What is the best way to initialize a JavaScript Date to midnight

Question

What is the simplest way to obtain an instance of new Date   but set the time at midnight

User · Answer

You can probably use   new Date   setUTCHours 0 0 0 0    if you need the value only once

User · Answer

Just going to add this here because I landed on this page looking for how to do this in moment js and others may do too     Rationale  the word  moment  already appears elsewhere on this page so search engines direct here  and moment js is widespread enough to warrant to being covered going on how often it is mentioned in other date-related SO questions   So  in version 2 0 0 and above   date startOf  day      For earlier versions   date sod      Docs   http   momentjs com docs   manipulating start-of

User · Answer

The setHours method can take optional minutes  seconds and ms arguments  for example   var d   new Date    d setHours 0 0 0 0     That will set the time to 00 00 00 000 of your current timezone  if you want to work in UTC time  you can use the setUTCHours method

User · Answer

I have made a couple prototypes to handle this for me      This is a safety check to make sure the prototype is not already defined  Function prototype method   function  name  func        if   this prototype name             this prototype name    func          return this            Date method  endOfDay   function          var date   new Date this       date setHours 23  59  59  999       return date       Date method  startOfDay   function          var date   new Date this       date setHours 0  0  0  0       return date        if you dont want the saftey check  then you can just use  Date prototype startOfDay   function        Method body here        Example usage   var date   new Date   now          now   requires jQuery console log  startOfDay      date startOfDay     console log  endOfDay      date endOfDay

User · Answer

In case you already have d3 js as a dependency in your project  or don t mind bringing it in  d3-time  d3 js library is modular as of v4 0 0  has got Intervals    They might prove useful when setting dates to  default  values  e g  midnight  0 00 seconds  the first of the month  etc    var d   new Date       Wed Aug 02 2017 15 01 07 GMT 0200  CEST  d3 timeHour d     Wed Aug 02 2017 00 00 00 GMT 0200  CEST  d3 timeMonth d     Tue Aug 01 2017 00 00 00 GMT 0200  CEST

User · Answer

If calculating with dates summertime will cause often 1 uur more or one hour less than midnight  CEST   This causes 1 day difference when dates return  So the dates have to round to the nearest midnight  So the code will be  ths to jamisOn        var d   new Date        if d getHours    lt  12        d setHours 0 0 0 0      previous midnight day       else       d setHours 24 0 0 0      next midnight day

User · Answer

Adding usefulness to  Dan s example  I had the need to find the next midday or midnight   var d   new Date    if d getHours    lt  12       d setHours 12 0 0 0      next midnight midday is midday   else      d setHours 24 0 0 0      next midnight midday is midnight     This allowed me to set a frequency cap for an event  only allowing it to happen once in the morning and once in the afternoon for any visitor to my site  The date captured was used to set the expiration of the cookie

User · Answer

Just wanted to clarify that the snippet from accepted answer gives the nearest midnight in the past   var d   new Date    d setHours 0 0 0 0      last midnight   If you want to get the nearest midnight in future  use the following code   var d   new Date    d setHours 24 0 0 0      next midnight

User · Answer

A one-liner for object configs   new Date new Date   setHours 0 0 0 0      When creating an element   dateFieldConfig           name   mydate         value  new Date new Date   setHours 0  0  0  0

[javascript] What is the best way to initialize a JavaScript Date to midnight?

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