css 级别_为什么没有CSS4-解释CSS级别

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We had CSS1, and CSS2. We even had CSS2.1 and we then moved onto CSS3 – or did we? This post is a quick explanation of how CSS is versioned today.

我们有CSS1和CSS2。 我们甚至有CSS2.1，然后又转向CSS3 –还是？ 这篇文章是今天CSS如何版本化的快速解释。

CSS versions 1 and 2 were monolithic specifications. All of CSS was included in one massive document. Selectors, positioning, colour – it was all in there.

CSS版本1和2是整体规范。 所有CSS都包含在一个庞大的文档中。 选择器，位置，颜色–都在那里。

The problem with monolithic specifications is that in order to finish the spec, every component part also has to be finished. As CSS has grown in complexity, and new features are added, it doesn’t make sense to draw a line at which all work is stopped on all parts of CSS in order to declare that CSS version finished. Therefore, after CSS2.1 all the things that had been part of the 2.1 specification were broken down into modules. As the new CSS modules included all that had gone before plus any new features, they all came into being at Level 3. Hence CSS3, and people like me who understood CSS as a single specification referred to the group of Level 3 modules as “CSS3”.

整体规格的问题在于，为了完成规格，每个组件也必须完成。 随着CSS的复杂性增加和添加新功能，画一条线停止在CSS的所有部分上停止所有工作以声明CSS版本完成是没有意义的 。 因此，在CSS2.1之后，属于2.1规范的所有内容都分解为模块。 由于新的CSS模块包含了以前的所有功能以及所有新功能，因此它们都诞生于3级。因此CSS3和像我这样将CSS理解为单一规范的人将3级模块组称为“ CSS3”。 ”。

While referring to all new CSS as CSS3 worked for a short time, it doesn’t reflect the reality of where CSS is today. If you read something about CSS3 Selectors, then what is actually being described is something that is part of the CSS Selectors Level 3 specification. In fact CSS Selectors is one of the specifications that is marked as completed and a Recommendation. The CSS Working Group is now working on Selectors Level 4 with new proposed features plus the selectors that were part of Level 3 (and CSS 1 and 2). It’s not CSS4, but Level 4 of a single specification. One small part of CSS.

虽然将所有新CSS称为CSS3的工作时间很短，但这并不能反映CSS的现状。 如果您阅读有关CSS3选择器的内容，那么实际上所描述的内容就是CSS选择器3级规范的一部分。 实际上， CSS选择器是标记为已完成的规范之一，也是建议书。 CSS工作组现在正在使用新提议的功能以及第3级（以及CSS 1和2）的选择器来开发第4级选择器。 它不是CSS4 ，而是单一规范的第4级。 CSS的一小部分。

We also have specifications for features that were never part of CSS 1 or 2, and so these specifications are at Level 1. They are brand new. Examples of Level 1 specifications are CSS Grid Layout and Flexbox. Flexbox is already a Candidate Recommendation (CR), Grid has been voted to CR too. Therefore any new features that are proposed are at this point likely to end up in the next Level of these specifications – Flexbox Level 2 and CSS Grid Level 2.

我们还提供了CSS 1或2从未包含的功能规范，因此这些规范处于1级。它们是全新的。 1级规范的示例包括CSS Grid Layout和Flexbox 。 Flexbox已经是候选人推荐（CR），Grid也被投票给CR。 因此，此时提出的任何新功能都可能会在这些规范的下一个级别（Flexbox级别2和CSS Grid级别2​​）中结束。

If you want to see the status of various CSS features, and the level they are currently at check out the CSS Working Group Current Work document. To understand the different statuses that a specification moves through, see the information on Maturity Levels in the Process document.

如果要查看各种CSS功能的状态及其当前级别，请查看CSS Working Group 当前工作文档 。 要了解规范所经历的不同状态，请参见过程文档中有关成熟度级别的信息。

翻译自: https://rachelandrew.co.uk/archives/2016/09/13/why-there-is-no-css4-explaining-css-levels/

css 级别