| title | slug |
|---|---|
<frequency> |
Web/CSS/frequency |
{{CSSRef}}
<frequency> CSS数据类型表示频率维度，例如语音的音高。目前它未在任何 CSS 属性中被使用。
The <frequency> data type consists of a {{cssxref("<number>")}} followed by one of the units listed below. As with all CSS dimensions, there is no space between the unit literal and the number.
可以使用以下单位：
Hz- : 表示以赫兹（hertz）为单位的频率。例如：
0Hz、1500Hz、10000Hz。
- : 表示以赫兹（hertz）为单位的频率。例如：
kHz- : 表示以千赫兹（kilohertz）为单位的频率。例如：
0kHz、1.5kHz、10kHz。
- : 表示以千赫兹（kilohertz）为单位的频率。例如：
Note
Although the number 0 is always the same regardless of unit, the unit may not be omitted. In other words, 0 is invalid and does not represent 0Hz or 0kHz. Though the units are case-insensitive, it is good practice to use a capital "H" for Hz and kHz, as specified in the SI.
12Hz Positive integer
4.3Hz Non-integer
14KhZ The unit is case-insensitive, though non-SI capitalization is not recommended.
+0Hz Zero, with a leading + and a unit
-0kHz Zero, with a leading - and a unit
12.0 This is a <number>, not an <frequency>, because it is missing a unit.
7 Hz No space is allowed between the number and the unit.
0 Although unitless zero is an allowable <length>, it's an invalid <frequency>.
{{Specifications}}
Note
This data type was initially introduced in CSS Level 2 for the now-obsolete aural media type, where it was used to define the pitch of the voice. However, the <frequency> data type has been reintroduced in CSS3, though no CSS property is using it at the moment.
{{Compat}}