Date

The Date general HTTP header contains the date and time at which the message originated.

Warning: Date is listed in the forbidden header names in the fetch spec, so this code will not send the Date header:

fetch('https://httpbin.org/get', {
  'headers': {
    'Date': (new Date()).toUTCString()
  }
})

Header type	Request header, Response header
Forbidden header name	yes

Syntax

Date: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT

<day-name>: One of "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", or "Sun" (case-sensitive).
<day>: 2 digit day number, e.g. "04" or "23".
<month>: One of "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec" (case sensitive).
<year>: 4 digit year number, e.g. "1990" or "2016".
<hour>: 2 digit hour number, e.g. "09" or "23".
<minute>: 2 digit minute number, e.g. "04" or "59".
<second>: 2 digit second number, e.g. "04" or "59".
GMT: Greenwich Mean Time. HTTP dates are always expressed in GMT, never in local time.

Date: Wed, 21 Oct 2015 07:28:00 GMT

new Date().toUTCString()
// "Mon, 09 Mar 2020 08:13:24 GMT"

Specification
HTTP Semantics # field.date

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	WebView Android	Chrome Android	Firefox for Android	Opera Android	Safari on IOS	Samsung Internet
`Date`	Yes	12	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes	Yes