This is an experimental technology
Check the Browser compatibility table carefully before using this in production.
Draft
This page is not complete.
Note: This feature is not supported by any user agent and its specifics are subject to change.
The prefers-reduced-data
CSS media feature is used to detect if the user has requested the web content that consumes less internet traffic.
Syntax
no-preference
- Indicates that the user has made no preference known to the system. This keyword value evaluates as false in the boolean context.
reduce
- Indicates that user has expressed the preference for lightweight alternate content.
User preferences
Currently no user agent implements this feature, although various operating systems do support such preferences and if this media query is ever implemented user agents will likely rely on the settings provided by the operating system.
Examples
Note: No browser currently implements this feature so the following example will not work.
In this example the montserrat-regular.woff2
font file will neither be preloaded nor downloaded if the user prefers reduced data, in this case the "system font stack" will serve as the fallback font:
HTML
<head> <link rel="preload" href="fonts/montserrat-regular.woff2" as="font" media="(prefers-reduced-data: no-preference)" crossorigin> <link rel="stylesheet" href="style.css"> </head>
CSS
@media (prefers-reduced-data: no-preference) { @font-face { font-family: Montserrat; font-style: normal; font-weight: 400; font-display: swap; /* latin */ src: local('Montserrat Regular'), local('Montserrat-Regular'), url('fonts/montserrat-regular.woff2') format('woff2'); unicode-range: U+0000-00FF, U+0131, U+0152-0153, U+02BB-02BC, U+02C6, U+02DA, U+02DC, U+2000-206F, U+2074, U+20AC, U+2122, U+2191, U+2193, U+2212, U+2215, U+FEFF, U+FFFD; } } body { font-family: Montserrat, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, "Microsoft YaHei", sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol"; }
Result
Specifications
Specification | Status | Comment |
---|---|---|
Media Queries Level 5 The definition of 'reduced-data' in that specification. |
Editor's Draft | Initial definition. |
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
prefers-reduced-data media feature | Chrome
Full support
85
| Edge
Full support
85
| Firefox No support No | IE No support No | Opera No support No | Safari No support No | WebView Android
No support
No
| Chrome Android
Full support
85
| Firefox Android No support No | Opera Android No support No | Safari iOS No support No | Samsung Internet Android No support No |
Legend
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.
- Experimental. Expect behavior to change in the future.
- See implementation notes.
- See implementation notes.
- User must explicitly enable this feature.
- User must explicitly enable this feature.
See also
Save-Data
HTTP header