update - CSS: Cascading Style Sheets 编辑

The update CSS media feature can be used to test how frequently (if at all) the output device is able to modify the appearance of content.

Syntax

The update feature is specified as a single keyword value chosen from the list below.

none

Once it has been rendered, the layout can no longer be updated. Example: documents printed on paper.

slow

The layout may change dynamically according to the usual rules of CSS, but the output device is not able to render or display changes quickly enough for them to be perceived as a smooth animation. Examples: e-book readers or severely underpowered devices.

fast

The layout may change dynamically according to the usual rules of CSS, and the output device is not unusually constrained in speed, so regularly-updating things like CSS Animations can be used. Example: computer screens.

Examples

HTML

<p>If this text animates for you, you are using a fast-updating device.</p>

CSS

@keyframes jiggle {
  from {
    transform: translateY(0);
  }

  to {
    transform: translateY(25px);
  }
}

@media (update: fast) {
  p {
    animation: 1s jiggle linear alternate infinite;
  }
}

Result

Specifications

Browser compatibility

BCD tables only load in the browser

See also

• Using Media Queries
• @media