Please note, this is a STATIC archive of website developer.mozilla.org from 03 Nov 2016, cach3.com does not collect or store any user information, there is no "phishing" involved.

Pragma

我们的志愿者还没有将这篇文章翻译为 中文 (简体)加入我们帮助完成翻译!

The Pragma HTTP/1.0 general header is an implementation-specific header that may have various effects along the request-response chain. It is used for backwards compatibility with HTTP/1.0 caches where the Cache-Control HTTP/1.1 header is not yet present.

Note: Pragma is not specified for HTTP responses and is therefore not a reliable replacement for the general HTTP/1.1 Cache-Control header, although it does behave the same as Cache-Control: no-cache, if the Cache-Control header field is omitted in a request. Use Pragma only for backwards compatibility with HTTP/1.0 clients.

Header type General header, but response behavior is not specified and thus implementation-specific.
Forbidden header name no
CORS-safelisted response-header yes

Syntax

Pragma: no-cache

Directives

no-cache

Same as Cache-Control: no-cache. Forces caches to submit the request to the origin server for validation before releasing a cached copy.

Examples

Pragma: no-cache

Specifications

Specification Title
RFC 7234, section 5.4: Pragma Hypertext Transfer Protocol (HTTP/1.1): Caching

Browser compatibility

Feature Chrome Edge Firefox Internet Explorer Opera Safari Servo
Basic Support(Yes)(Yes)(Yes)(Yes)(Yes)(Yes)(Yes)
Feature Android Chrome for Android Edge Mobile Firefox for Android IE Mobile Opera Mobile Safari Mobile
Basic Support(Yes)(Yes)(Yes)(Yes)(Yes)(Yes)(Yes)

See also

文档标签和贡献者

 此页面的贡献者: fscholz, teoli
 最后编辑者: fscholz,