W3cubDocs

/HTTP

If-Range

The If-Range HTTP request header makes a range request conditional: if the condition is fulfilled, the range request will be issued and the server sends back a 206 Partial Content answer with the appropriate body. If the condition is not fulfilled, the full resource is sent back, with a 200 OK status.

This header can be used either with a Last-Modified validator, or with an ETag, but not with both.

The most common use case is to resume a download, to guarantee that the stored resource has not been modified since the last fragment has been received.

Syntax

If-Range: <day-name>, <day> <month> <year> <hour>:<minute>:<second> GMT
If-Range: <etag>

Directives

<etag>
An entity tag uniquely representing the requested resource. It is a string of ASCII characters placed between double quotes (Like "675af34563dc-tr34") and may be prefixed by W/ to indicate that the weak comparison algorithm should be used.
<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.

Examples

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

Specifications

Specification Title
RFC 7233, section 3.2: If-Range Hypertext Transfer Protocol (HTTP/1.1): Range Requests

Browser compatibility

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

See also

© 2005–2017 Mozilla Developer Network and individual contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/If-Range