hint for HTTP compression related best practices
npm install @hint/hint-http-compressionhttp-compression)http-compression warns against serving resources uncompressed
or using an inappropriate encoding.
One of the fastest and easiest ways one can improve web site/app
performance is to reduce the amount of data sent to the client
by using HTTP compression. This not only [reduces the data used by
the user][wdmsc], but can also significantly cut down on the server
costs.
Here are a few rules to follow to get the most out of compressing
resources:
* Only compress resources for which the result of the compression
will be smaller than original size.
In general text-based resources (HTML, CSS, JavaScript, SVGs, etc.)
compress very well especially if the file is not very small.
The same goes for some other file formats (e.g.: ICO files, web fonts
such as EOT, OTF, and TTF, etc.)
However, compressing resources that are already compressed (e.g.:
images, audio files, PDFs, etc.) not only wastes CPU resources, but
usually results in little to no reduction, or in some cases, results
in an increase in file size.
The same applies to resources that are very small because of the
overhead of compression file formats.
* Use the most efficient compression method.
gzip is the most used encoding method currently as it strikes a
good balance between compression ratio (as [high as 70%][gzip ratio]
especially for larger files) and encoding time and is supported
pretty much everywhere.
Better savings can be achieved using [Zopfli][zopfli] which
can reduce the size on average [3–8% more than gzip][zopfli
blog post]. Since Zopfli output (for the gzip option) is valid
gzip content, Zopfli works everywhere gzip works. The only down
side is that encoding takes more time than gzip, making Zopfli
more suitable for static content (i.e. encoding resources as part
of a build script, not on the fly).
Things can be improved even further using [Brotli][brotli].
This encoding can achieve [20–26% higher compression ratios][brotli
blog post] over Zopfli. However, this encoding is not compatible
with gzip, limiting the support to modern browsers and its usage to
[only over HTTPS (as proxies misinterpret unknown encodings)][brotli
over https].
As a rule, for best performance and compatibility, resources
should be served compressed with Zopfli over insecure HTTP, and
Brotli when sending over HTTPS with a fallback to Zopfli if HTTPS
is not supported.
* Avoid using deprecated or not widely supported compression formats,
and Content-Type values.
Avoid using deprecated Content-Type values such as x-gzip. Some
user agents may alias them to the correct, current equivalent value
(e.g.: alias x-gzip to gzip), but that is not always true.
Also avoid using encodings that are not widely supported (e.g.:
compress, bzip2, [sdch][unship sdch], etc.), and/or may not
be as efficient, or can create problems (e.g.: [deflate][deflate
issues]).
* Avoid potential caching related issues.
When resources are served compressed, they should be served with
the Vary header containing the Accept-Encoding value (or with
something such as Cache-Control: private that prevents caching
in proxy caches and such altogether).
This needs to be done to avoid problems such as an intermediate proxy
caching the compressed version of the resource and then sending it
to all user agents, whether they support that encoding
or even requested the compressed version.
* Resources should be served compressed only when requested as such,
appropriately encoded, and without relying on user agent sniffing.
The Accept-Encoding request header specified should be respected.
Sending a resource encoded with a different encoding than one of the
ones accepted can lead to problems.
Here are some examples:
* If the user agent makes a request containing the [Accept-Encoding:][identity] header, that means it wants the response to
identity
not be transformed in any way, so the server should send the data
uncompress.
* If the user agent makes a request containing the Accept-Encoding: header, that means it wants the response to either be
gzip, br
uncompress or compress with one of the specified encodings, namely:
gzip (or the gzip compatible Zopfli) or Brotli. In the optimal case,
the server sends the data compress with Zopfli over HTTP, and Brotli
over HTTPS.
* Dealing with special cases.
One such special case is SVGZ files that are SVG files
compressed with gzip. Since they are already compressed, they
shouldn't be compressed again. However, sending them without the
Content-Encoding: gzip header will create problems as user agents
will not know they need to decompress before trying to display them.
The hint checks for the use cases previously specified. Namely, it
checks that:
* Only resources for which the result of the compression is smaller
than original size are served compressed.
* The most efficient encodings are used (by default the hint check if
Zopfli is used over HTTP and Brotli over HTTPS, however that can
be changed, see: Can the hint be configured?
section).
* Deprecated or not widely supported encodings, and Content-Type
values are not used.
* Potential caching related issues are avoided.
* Resources are served compressed only when requested as such, are
appropriately encoded, and no user-agent detection is done.
* Special cases (such as SVGZ) are handled correctly.
Resource that should be compressed is not served compressed.
e.g.: When the request for https://example.com/example.js contains
``text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Type: text/javascript
`
Resource that should not be compressed is served compressed.
e.g.: When the request for https://example.com/example.png contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Encoding: br
Content-Type: image/png
Vary: Accept-Encoding
`
Resource that compressed results in a bigger or equal size to the
uncompressed size is still served compressed.
e.g.: For http://example.com/example.js containing only const x = 5;,
using the defaults, the sizes may be as follows.
`text
original size: 13 bytes
gzip size: 38 bytes
zopfli size: 33 bytes
brotli size: 17 bytes
`
When the request for http://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate
response is
`text
HTTP/... 200 OK
...
Content-Encoding: gzip
Content-Type: text/javascript
Vary: Accept-Encoding
`
Resource that should be compressed is served compressed with deprecated
or disallowed compression method or Content-Encoding value.
e.g.: When the request for http://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate
response contains deprecated x-gzip value for Content-Encoding
`text
HTTP/... 200 OK
...
Content-Encoding: x-gzip
Content-Type: text/javascript
Vary: Accept-Encoding
`
response is compressed with disallowed compress compression method
`text
HTTP/... 200 OK
...
Content-Encoding: compress
Content-Type: text/javascript
Vary: Accept-Encoding
`
or response tries to use deprecated SDCH
`text
HTTP/... 200 OK
...
Content-Encoding: gzip,
Content-Type: text/javascript
Get-Dictionary: /dictionaries/search_dict, /dictionaries/help_dict
Vary: Accept-Encoding
`
Resource that should be compressed is not served compressed using
Zopfli over HTTP.
e.g.: When the request for http://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate
response is
`text
HTTP/... 200 OK
...
Content-Encoding: gzip
Content-Type: text/javascript
Vary: Accept-Encoding
`
Resource that should be compressed is served compressed using Brotli
over HTTP.
e.g.: When the request for http://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Encoding: br
Content-Type: text/javascript
Vary: Accept-Encoding
`
Resource that should be compressed is not served compressed using
Brotli over HTTPS.
e.g.: When the request for https://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Encoding: gzip
Content-Type: text/javascript
Vary: Accept-Encoding
`
Resource that is served compressed doesn't account for caching
(e.g.: is not served with the Vary header with the Accept-Encoding
value included, or something such as ).
e.g.: When the request for https://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Encoding: br
Content-Type: text/javascript
`
Resource is blindly served compressed using gzip no matter what the
user agent advertises as supporting.
E.g.: When the request for https://example.com/example.js contains
`text`
...
Accept-Encoding: br
response is
`text
HTTP/... 200 OK
...
Content-Encoding: gzip
Content-Type: text/javascript
Vary: Accept-Encoding
`
Resource is served compressed only for certain user agents.
E.g.: When the request for https://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate, br
User-Agent: Mozilla/5.0 Gecko
response is
`text
HTTP/... 200 OK
...
Content-Type: text/javascript
`
however, when requested with
`text`
...
Accept-Encoding: gzip, deflate, br
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.13; rv:57.0) Gecko/20100101 Firefox/57.0
response is
`text
HTTP/... 200 OK
...
Content-Encoding: br
Content-Type: text/javascript
Vary: Accept-Encoding
`
SVGZ resource is not served with Content-Encoding: gzip header:
E.g.: When the request for https://example.com/example.svgz contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Type: image/svg+xml
`
Resource that should be compressed is served compressed using Zopfli
over HTTP and with the Vary: Accept-Encoding header.
e.g.: When the request for http://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate
response is
`text
HTTP/... 200 OK
...
Content-Encoding: gzip
Content-Type: text/javascript
Vary: Accept-Encoding
`
Resource that should be compressed is served compressed using Brotli
over HTTPS and with the Vary: Accept-Encoding header.
e.g.: When the request for https://example.com/example.js contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Encoding: br
Content-Type: text/javascript
Vary: Accept-Encoding
`
Resource that should not be compressed is not served compressed.
e.g.: When the request for https://example.com/example.png contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Type: image/png
`
SVGZ resource is served with Content-Encoding: gzip header:
e.g.: When the request for https://example.com/example.svgz contains
`text`
...
Accept-Encoding: gzip, deflate, br
response is
`text
HTTP/... 200 OK
...
Content-Encoding: gzip
Content-Type: image/svg+xml
`
How to configure Apache
Apache can be configured to conditionally (based on media type)
compress resources using gzip as well as send the appropriate
Content-Encoding and Vary headers using [mod_deflate][mod_deflate]AddOutputFilterByType
and the [ directive][addoutputfilterbytype].
For Zopfli, there isn't a core Apache module or directive to do it,
However, since compressing things using Zopfli takes more time, it's
usually indicated to do it as part of your build step. Once that is
done, Apache needs to be configure to server those pre-compressed
files when gzip compression is requested by the user agent.
Starting with Apache v2.4.26, [mod_brotli][mod_brotli] and theAddOutputFilterByType
[ directive][addoutputfilterbytype] can be usedContent-Encoding
to conditionally compress with Brotli as well as add the and Vary headers. However, like Zopfli, Brotli canmod_brotli
take more time. So, when provided, may be used to compress
dynamic resources (especially if set to use lower compression quality
levels), but for static resources it's indicated to compress them as
part of the build process and configure Apache to serve those
pre-compressed resources whenever Brotli compression is requested over
HTTPS.
If you don't want to start from scratch, below is a generic starter
snippet that contains the necessary configurations to ensure that
commonly used file types are served compressed and with the appropriate
headers, and thus, make your web site/app pass this hint.
Important notes:
* The following relies on Apache being configure to have the correct
filename extensions to media types mappings (see Apache section from
content-type hint).
* For Zopfli and Brotli this snippet assumes that running the build
step will result in 3 version for every resource:
* the original (e.g.: script.js) - you should also have this file
in case the user agent doesn't requests things compressed
* the file compressed with Zopfli (e.g.: script.js.gz)
* the file compressed with Brotli (e.g.: script.js.br)
`apache
# Turn on the rewrite engine (this is necessary in order for
# the RewriteRule directives to work).
#
# https://httpd.apache.org/docs/current/mod/core.html#options
RewriteEngine On
# Enable the FollowSymLinks option if it isn't already.
#
# https://httpd.apache.org/docs/current/mod/core.html#options
Options +FollowSymlinks
# If the web host doesn't allow the FollowSymlinks option,
# it needs to be comment out or removed, and then the following
# uncomment, but be aware of the performance impact.
#
# https://httpd.apache.org/docs/current/misc/perf-tuning.html#symlinks
# Options +SymLinksIfOwnerMatch
# Depending on how the server is set up, you may also need to
# use the RewriteOptions directive to enable some options for
# the rewrite engine.
#
# https://httpd.apache.org/docs/current/mod/mod_rewrite.html#rewriteoptions
# RewriteBase /
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# 1) Brotli
# If Accept-Encoding header contains br
RewriteCond "%{HTTP:Accept-encoding}" "br"
# and the request is made over HTTPS.
RewriteCond "%{HTTPS}" "on"
# The Brotli pre-compressed version of the file exists
# (e.g.: script.js is requested and script.js.gz exists).
RewriteCond "%{REQUEST_FILENAME}\.br" "-s"
# Then, serve the Brotli pre-compressed version of the file.
RewriteRule "^(.*)" "$1\.br" [QSA]
# Set the correct media type of the requested file. Otherwise,
# it will be served with the br media type since the file has
# the .br extension.
#
# Also, set the special purpose environment variables so
# that Apache doesn't recompress these files.
RewriteRule "\.(ico|cur)\.br$" "-" [T=image/x-icon,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.(md|markdown)\.br$" "-" [T=text/markdown,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.appcache\.br$" "-" [T=text/cache-manifest,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.atom\.br$" "-" [T=application/atom+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.bmp\.br$" "-" [T=image/bmp,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.css\.br$" "-" [T=text/css,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.eot.\.br$" "-" [T=application/vnd.ms-fontobject,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.geojson\.br$" "-" [T=application/vnd.geo+json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.html?\.br$" "-" [T=text/html,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.ics\.br$" "-" [T=text/calendar,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.json\.br$" "-" [T=application/json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.jsonld\.br$" "-" [T=application/ld+json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.m?js\.br$" "-" [T=text/javascript,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.otf\.br$" "-" [T=font/otf,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.rdf\.br$" "-" [T=application/rdf+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.rss\.br$" "-" [T=application/rss+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.svg\.br$" "-" [T=image/svg+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.ttc\.br$" "-" [T=font/collection,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.ttf\.br$" "-" [T=font/ttf,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.txt\.br$" "-" [T=text/plain,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.vc(f|ard)\.br$" "-" [T=text/vcard,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.vtt\.br$" "-" [T=text/vtt,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.webmanifest\.br$" "-" [T=application/manifest+json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.xhtml\.br$" "-" [T=application/xhtml+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.xml\.br$" "-" [T=text/xml,E=no-brotli:1,E=no-gzip:1]
# Set the Content-Encoding header.
Header append Content-Encoding br
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# 2) Zopfli
# If Accept-Encoding header contains gzip and the
# request is made over HTTP.
RewriteCond "%{HTTP:Accept-encoding}" "gzip"
# The Zopfli pre-compressed version of the file exists
# (e.g.: script.js is requested and script.js.gz exists).
RewriteCond "%{REQUEST_FILENAME}\.gz" "-s"
# Then serve the Zopfli pre-compressed version of the file.
RewriteRule "^(.*)" "$1\.gz" [QSA]
# Set the media types of the file, as otherwise, because
# the file has the .gz extension, it wil be served with
# the gzip media type.
#
# Also, set the special purpose environment variables so
# that Apache doesn't recompress these files.
RewriteRule "\.(ico|cur)\.gz$" "-" [T=image/x-icon,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.(md|markdown)\.gz$" "-" [T=text/markdown,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.appcache\.gz$" "-" [T=text/cache-manifest,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.atom\.gz$" "-" [T=application/atom+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.bmp\.gz$" "-" [T=image/bmp,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.css\.gz$" "-" [T=text/css,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.eot.\.gz$" "-" [T=application/vnd.ms-fontobject,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.geojson\.gz$" "-" [T=application/vnd.geo+json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.html?\.gz$" "-" [T=text/html,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.ics\.gz$" "-" [T=text/calendar,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.json\.gz$" "-" [T=application/json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.jsonld\.gz$" "-" [T=application/ld+json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.m?js\.gz$" "-" [T=text/javascript,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.otf\.gz$" "-" [T=font/otf,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.rdf\.gz$" "-" [T=application/rdf+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.rss\.gz$" "-" [T=application/rss+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.svg\.gz$" "-" [T=image/svg+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.ttc\.gz$" "-" [T=font/collection,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.ttf\.gz$" "-" [T=font/ttf,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.txt\.gz$" "-" [T=text/plain,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.vc(f|ard)\.gz$" "-" [T=text/vcard,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.vtt\.gz$" "-" [T=text/vtt,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.webmanifest\.gz$" "-" [T=application/manifest+json,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.xhtml\.gz$" "-" [T=application/xhtml+xml,E=no-brotli:1,E=no-gzip:1]
RewriteRule "\.xml\.gz$" "-" [T=text/xml,E=no-brotli:1,E=no-gzip:1]
# Set the Content-Encoding header.
Header append Content-Encoding gzip
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Set the Vary header.
Header append Vary Accept-Encoding
# 3) gzip
#
# [!] For Apache versions below version 2.3.7 you don't need to
# enable mod_filter and can remove the
# and lines as AddOutputFilterByType is still in
# the core directives.
#
# https://httpd.apache.org/docs/current/mod/mod_filter.html#addoutputfilterbytype
AddOutputFilterByType DEFLATE "application/atom+xml" \
"application/json" \
"application/manifest+json" \
"application/rdf+xml" \
"application/rss+xml" \
"application/schema+json" \
"application/vnd.ms-fontobject" \
"application/xhtml+xml" \
"font/collection" \
"font/opentype" \
"font/otf" \
"font/ttf" \
"image/bmp" \
"image/svg+xml" \
"image/x-icon" \
"text/cache-manifest" \
"text/css" \
"text/html" \
"text/javascript" \
"text/plain" \
"text/vtt" \
"text/xml"
# - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
# Special case: SVGZ
#
# If these files type would be served without the
# Content-Enable: gzip response header, user agents would
# not know that they first need to uncompress the response,
# and thus, wouldn't be able to understand the content.
AddEncoding gzip svgz
`
Also note that:
* The above snippet works with Apache v2.2.0+, but you need tomod_deflate
have [][mod_deflate], [mod_mime][mod_mime],mod_rewrite
[][mod_rewrite], and for Apache versions belowv2.3.7
[mod_filter][mod_filter] [enabled][how to enable apache
modules] in order for it to take effect.
* If you have access to the [main Apache configuration file][main
apache conf file] (usually called httpd.conf), you should add
the logic in, for example, a [][apache directory].htaccess
section in that file. This is usually the recommended way as
[using files slows down][htaccess is slow] Apache!
If you don't have access to the main configuration file (quite
common with hosting services), add the snippets in a .htaccess
file in the root of the web site/app.
For the complete set of configurations, not just for this rule, see
the [Apache server configuration related documentation][apache config].
How to configure IIS
IIS 7+ can be configured to compress responses (static or dynamic)
via the [][urlcompression].
For Zopfli, there isn't a core IIS module to do it. However, since
compressing things using Zopfli takes more time, it's usually indicated
to do it as part of your build step. Once that is done, IIS needs to
be configured to server those pre-compressed files when gzip compression
is requested by the user agent.
Brotli, like Zopfli, takes more time. It's indicated to compress
resources at build time, and configure IIS to serve those pre-compressed
resources whenever Brotli compression is requested over HTTPS by the
user agent.
If you don't want to start from scratch, below is a generic starter
snippet that contains the necessary configurations to ensure that
commonly used file types are served compressed and with the appropriate
headers, and thus, make your web site/app pass this hint.
Important notes:
* The following relies on IIS being configured to have the correct
filename extensions to media types mappings (see IIS section from
content-type rule).
* For Zopfli and Brotli this snippet assumes that running the build
step will result in 3 version for every resource:
* the original (e.g.: script.js) - you should also have this file
in case the user agent doesn't requests things compressed
* the file compressed with Zopfli (e.g.: script.js.gz)
* the file compressed with Brotli (e.g.: script.js.br)
`xml
`
Note that:
* The above snippet works with IIS 7+.
* You should use the above snippet in the web.config of your
application.
For the complete set of configurations, not just for this rule,
see the [IIS server configuration related documentation][iis config].
If you prefer to let IIS compress your assets using Brotli, you can
use the [IIS compression scheme providers][iis compression]. However,
make sure to read [how to enable multiple compression schemes][multiple
compression schemes] and the priority limitations in some versions.
You can override the defaults by specifying what type of compression
you don't want the hint to check for. This can be done for the html
(main page) and/or the the hint determines should be served
compressed, using the following format:
In the [.hintrc][hintrc] file:
`json`
{
"connector": {...},
"formatters": [...],
"hints": {
"http-compression": [ "warning", {
"resource": {
"
"threshold":
...
},
"html": {
"
"threshold":
...
}
},
...
},
...
}
Where can be one of: brotli, gzip, orzopfli.threshold
And is the maximum size (in bytes) to set thehint
severity of a report to ..hintrc
E.g. If you want the hint to check if only the page resources are
served compressed using Brotli, and not the page itself, you can
use the following configuration in the [][hintrc]:
`json`
{
"connector": {...},
"formatters": [...],
"hints": {
"http-compression": [ "warning", {
"html": {
"brotli": false,
"threshold": 1024
}
}],
...
},
...
}
Note: You can also use the [ignoredUrls][ignoring domains].hintrc
property from the file to exclude domains you don’t control
(e.g.: CDNs) from these checks.
This package is installed automatically by webhint:
`bash`
npm install hint --save-dev
To use it, activate it via the [.hintrc][hintrc] configuration file:
`json`
{
"connector": {...},
"formatters": [...],
"hints": {
"http-compression": "error",
...
},
"parsers": [...],
...
}
Note: The recommended way of running webhint is as a devDependency` of
your project.
[brotli]: https://github.com/google/brotli
[brotli blog post]: https://opensource.googleblog.com/2015/09/introducing-brotli-new-compression.html
[brotli over https]: https://medium.com/@yoavweiss/well-the-technical-reason-for-brotli-being-https-only-is-that-otherwise-there-s-a-very-high-508f15f0ad95
[deflate issues]: https://stackoverflow.com/questions/9170338/why-are-major-web-sites-using-GZIP/9186091#9186091
[gzip is not enough]: https://www.youtube.com/watch?v=whGwm0Lky2s
[gzip ratio]: https://www.youtube.com/watch?v=Mjab_aZsdxw&t=24s
[hintrc]: https://webhint.io/docs/user-guide/configuring-webhint/summary/
[identity]: https://tools.ietf.org/html/rfc2616#page-24
[unship sdch]: https://groups.google.com/a/chromium.org/forum/#!topic/blink-dev/nQl0ORHy7sw
[wdmsc]: https://whatdoesmysitecost.com/
[zopfli]: https://github.com/google/zopfli
[zopfli blog post]: https://developers.googleblog.com/2013/02/compress-data-more-densely-with-zopfli.html
[addoutputfilterbytype]: https://httpd.apache.org/docs/2.4/mod/mod_filter.html#addoutputfilterbytype
[apache config]: https://webhint.io/docs/user-guide/server-configurations/apache/
[apache directory]: https://httpd.apache.org/docs/current/mod/core.html#directory
[how to enable apache modules]: https://github.com/h5bp/server-configs-apache/tree/7eb30da6a06ec4fc24daf33c75b7bd86f9ad1f68#enable-apache-httpd-modules
[htaccess is slow]: https://httpd.apache.org/docs/current/howto/htaccess.html#when
[main apache conf file]: https://httpd.apache.org/docs/current/configuring.html#main
[mod_brotli]: https://httpd.apache.org/docs/trunk/mod/mod_brotli.html
[mod_deflate]: https://httpd.apache.org/docs/current/mod/mod_deflate.html
[mod_filter]: https://httpd.apache.org/docs/current/mod/mod_filter.html
[mod_mime]: https://httpd.apache.org/docs/current/mod/mod_mime.html
[mod_rewrite]: https://httpd.apache.org/docs/current/mod/mod_rewrite.html
[iis compression]: https://docs.microsoft.com/en-us/iis/extensions/iis-compression/iis-compression-overview
[iis config]: https://webhint.io/docs/user-guide/server-configurations/iis/
[multiple compression schemes]: https://docs.microsoft.com/en-us/iis/extensions/iis-compression/using-iis-compression#enabling-multiple-compression-schemes
[urlcompression]: https://docs.microsoft.com/en-us/iis/configuration/system.webserver/urlcompression
[ignoring domains]: https://webhint.io/docs/user-guide/configuring-webhint/ignoring-domains/