“所有”是否为媒体查询添加任何内容？ [英] Does 'all' add anything to a media query?

问题描述

是这样的：

@media all and (min-width: @medium-min) { }

与此相同：

@media (min-width: @medium-min) { }

看到为什么添加所有会产生任何区别，而不是指定。但我经常看到所有已添加。是否有边缘情况需要这个？

I cant see why adding 'all' would make any difference than not specifying. However I often see the 'all' has been added. Is there an edge case that requires this?

推荐答案

是的，默认情况下设置为all。

Yes it does and by default it's set to all.

所有设备都会收听此

All devices listen to this

可用的媒体类型：

Available media types:

• all： code>所有设备都会收听此


• braille：用于盲文触觉反馈设备。


• 浮雕用于分页盲文打印机。




• 打印用于分页材料，用于手持设备（智能手机和平板电脑不要
  听此！


• 投影用于投影演示，例如投影机。


• scree n主要用于彩色电脑萤幕和智慧型手机。


• 用于语音合成器..（无论可能是什么）


• tty -pitch字符网格（例如
  电传，终端或具有有限显示功能的便携式设备
  功能）。


• tv 用于电视类设备（低分辨率，彩色，
  有限 - 可滚动屏幕，可用音频）。

• all: All devices listen to this
• braille: Used for braille tactile feedback devices.
• embossed Used for paged braille printers.
• handheld Used for handheld devices (Smartphones and tablets do NOT listen to this!).
• print Used for paged material and for documents viewed on screen in print preview mode.
• projection Used for projected presentations, for example projectors.
• screen Used primarily for color computer screens and smartphones.
• speech Used for speech synthesizers.. (Whatever that may be)
• tty Used for media using a fixed-pitch character grid (such as teletypes, terminals, or portable devices with limited display capabilities).
• tv Used for television-type devices (low resolution, color, limited-scrollability screens, sound available).

参考： http://cssmediaqueries.com/what -are-css-media-queries.html

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