<frequency> - CSS（层叠样式表） 编辑

<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。

语法

The <frequency> data type consists of a <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.

单位

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。

kHz

表示以千赫兹（kilohertz）为单位的频率。例如：0kHz、1.5kHz、10kHz。

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.

示例

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

Invalid frequency values

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>.

规范

规范	状态	备注
CSS Values and Units Module Level 3 <frequency>	Candidate Recommendation	Initial definition

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.

浏览器兼容性

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