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

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