If-Unmodified-Since

Baseline Widely available

This feature is well established and works across many devices and browser versions. Itâs been available across browsers since Ð¸ÑÐ»Ñ 2015 Ð³..

Ð ÑÐ¾ÑÐµÑÐ°Ð½Ð¸Ð¸ Ñ Ð´ÑÑÐ³Ð¸Ð¼Ð¸ Ð½ÐµÐ±ÐµÐ·Ð¾Ð¿Ð°ÑÐ½ÑÐ¼Ð¸ Ð¼ÐµÑÐ¾Ð´Ð°Ð¼Ð¸, ÑÐ°ÐºÐ¸Ð¼Ð¸ ÐºÐ°Ðº POST, Ð¾Ð½ Ð¼Ð¾Ð¶ÐµÑ Ð¸ÑÐ¿Ð¾Ð»ÑÐ·Ð¾Ð²Ð°ÑÑÑÑ Ð´Ð»Ñ ÑÐµÐ°Ð»Ð¸Ð·Ð°ÑÐ¸Ð¸ optimistic concurrency control, Ð½Ð°Ð¿ÑÐ¸Ð¼ÐµÑ, ÑÐ´ÐµÐ»Ð°Ð½Ð½Ð¾Ð³Ð¾ Ð½ÐµÐºÐ¾ÑÐ¾ÑÑÐ¼Ð¸ Ð²Ð¸ÐºÐ¸-Ð²ÐµÑÑÐ¸ÑÐ¼Ð¸: Ð²ÑÐ¿ÑÑÐºÐ¸ Ð¾ÑÐºÐ»Ð¾Ð½ÑÑÑÑÑ, ÐµÑÐ»Ð¸ ÑÐ¾ÑÑÐ°Ð½ÑÐ½Ð½ÑÐ¹ Ð´Ð¾ÐºÑÐ¼ÐµÐ½Ñ Ð±ÑÐ» Ð¸Ð·Ð¼ÐµÐ½ÑÐ½ Ñ Ð¼Ð¾Ð¼ÐµÐ½ÑÐ° Ð²Ð¾ÑÑÑÐ°Ð½Ð¾Ð²Ð»ÐµÐ½Ð¸Ñ Ð¾ÑÐ¸Ð³Ð¸Ð½Ð°Ð»Ð°.

Ð ÑÐ¾ÑÐµÑÐ°Ð½Ð¸Ð¸ Ñ Ð·Ð°Ð¿ÑÐ¾ÑÐ¾Ð¼ Ð´Ð¸Ð°Ð¿Ð°Ð·Ð¾Ð½Ð° Ñ If-Range ÐµÐ³Ð¾ Ð¼Ð¾Ð¶Ð½Ð¾ Ð¸ÑÐ¿Ð¾Ð»ÑÐ·Ð¾Ð²Ð°ÑÑ Ð´Ð»Ñ Ð¾Ð±ÐµÑÐ¿ÐµÑÐµÐ½Ð¸Ñ ÑÐ¾Ð³Ð¾, ÑÑÐ¾Ð±Ñ Ð½Ð¾Ð²ÑÐ¹ ÑÑÐ°Ð³Ð¼ÐµÐ½Ñ Ð·Ð°Ð¿ÑÐ°ÑÐ¸Ð²Ð°Ð»ÑÑ Ð¸Ð· Ð½ÐµÐ¼Ð¾Ð´Ð¸ÑÐ¸ÑÐ¸ÑÐ¾Ð²Ð°Ð½Ð½Ð¾Ð³Ð¾ Ð´Ð¾ÐºÑÐ¼ÐµÐ½ÑÐ°.

Ð¢Ð¸Ð¿ Ð·Ð°Ð³Ð¾Ð»Ð¾Ð²ÐºÐ°	ÐÐ°Ð³Ð¾Ð»Ð¾Ð²Ð¾Ðº Ð·Ð°Ð¿ÑÐ¾ÑÐ°
ÐÐ°Ð¿ÑÐµÑÑÐ½Ð½Ð¾Ðµ Ð¸Ð¼Ñ Ð·Ð°Ð³Ð¾Ð»Ð¾Ð²ÐºÐ°	ÐÐµÑ

Ð¡Ð¸Ð½ÑÐ°ÐºÑÐ¸Ñ

If-Unmodified-Since: <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.

If-Unmodified-Since: Wed, 21 Oct 2015 07:28:00 GMT

Ð¡Ð¿ÐµÑÐ¸ÑÐ¸ÐºÐ°ÑÐ¸Ñ	ÐÐ°Ð³Ð¾Ð»Ð¾Ð²Ð¾Ðº
RFC 7232, ÑÐ°Ð·Ð´ÐµÐ» 3.4: If-Unmodified-Since	Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests

This page was last modified on 7 Ð¸ÑÐ». 2025 Ð³. by MDN contributors.