CSS 缩写

While Emmet abbreviations are good for generating HTML, XML or any other structured markup, it may look useless for CSS. You don’t want to write CSS selectors and transform them to CSS selectors, right? The only thing Emmet can do for you is to provide shorthands for CSS properties, but editors with native snippets and autocomplete can help you way better.

Emmet 能很好的用于生成HTML、XML等结构语言，而对 CSS 似乎没用。你不想书写选择器然后将它们转化为选择器，对吧？（译注：意思是指对于选择器没有意义） Emmet 能做的只是提供 CSS 属性简写，而编辑器原生代码片断与自动补全帮助更大。

Actually, Emmet has something to offer.

实际上 Emmet 能做一些事。

For CSS syntax, Emmet has a lot of predefined snippets for properties. For example, you can expand m abbreviation to get margin: ; snippet. But you don’t want just margin property, you want to specify a value for this property. So you have to manually type, let’s say, 10px .

对于 CSS, Emmet 有大量预定义的属性代码片断。例如展开缩写 m 得到 margin: ; 。但是你不只想得到 margin ，你想给这个属性指定一个值，于是你手动输入，比如说 10px 。

Emmet can greatly optimize your workflow here: you can inject value directly into abbreviation . To get margin: 10px; you can simply expand the m10 abbreviation. Want multiple values? Use a hypen to separate them: m10-20 expands to margin: 10px 20px; . Negative values? No problem: precede the first value with hyphen and all the rest with double hyphens: m-10--20 expands to margin: -10px -20px;

这里 Emmet 能大大优化你的工作流程：将值直接注入缩写。为了得到 margin: 10px; 只用简单的展开缩写 m10 。想要多个值？ 使用连字符分隔值： m10-20 展开为 margin: 10px 20px; 。负值？没问题，第一个值前放一个连字符，其它的值前放两个连字符： m-10--20 展开为 margin: -10px -20px; 。

Emmet has a special CSS resolver that expands such abbreviations into a complete CSS property.

Emmet 使用特别的 CSS 解析器将缩写展开为完整的 CSS 属性。

Here’s what happens when you expand m10 abbreviation.

下面是展开缩写 m10 的过程。

First, it looks for a m10 snippet definition in snippets.json . If it’s found, it simply outputs it as a regular snippet. Otherwise, it extracts value from abbreviation.

首先在 snippets.json 里查找定义 m10 。如果找到了则将它作为普通的代码片断输出。否则从缩写里提取值。

To provide best user experience, resolver doesn’t introduce any special value separator: it’s much faster to type m5 rather than m:5 . So it needs to find a value bound: a first occurrence of digit or hyphen is treated as a value bound . In m10 example, m is property part and 10 is value part .

为了提供最好的用户体验，解析器没有引入专门的值分隔符：输入 m5 比 m:5 快得多。这样需要查找值界定：最先出现的数字或连字符作为值界定。对于 m10 来说， m 是属性， 10 是值。

When property part is found, resolver searches for the snippet definition in snippets.json . For an m part, it will find "m": "margin:|;" definition ( | character is used as a caret position reference when the snippet is expanded).

当找到属性部分后，解析器在 snippets.json 里查找代码片断定义。对于 m , 找到定义 "m": "margin:|;" （ | 是缩写展开后的插入符位置）。

The snippet definition looks like a CSS property (this is very important!) so Emmet is able to split it to a CSS property and value and place transformed value part at caret position (the | character).

代码片断定义看着像 CSS 属性（这很重要！），这样 Emmet 能够将缩写分成属性与值两部分，并将转换后的值放到插入符的位置（由 | 指定）

By default, when you expand an abbreviation with integer value, Emmet outputs it with a px unit: m10 → margin: 10px; . If you’re expanding an abbreviation with a float value, it is outputted with an em unit: m1.5 → margin: 1.5em; . But you can explicitly provide the unit name, just by putting any alpha characters right after value: m1.5ex → margin: 1.5ex; , m10foo → margin: 10foo; .

当展开整数值时，Emmet 默认添加单位 px ，例如 m10 → margin: 10px; 。如果是展开浮点数值，添加单位 em ，例如 m1.5 → margin: 1.5em; 。不过可以显式地在值后面指定单位： m1.5ex → margin: 1.5ex; , m10foo → margin: 10foo; 。

If you’re explicitly defining units, you don’t need to use hyphens to separate values anymore: m10ex20em → margin: 10ex 20em; , m10ex-5 → margin: 10ex -5px; .

如果显式地指定单位，不再需要用连字号分隔值： m10ex20em → margin: 10ex 20em; , m10ex-5 → margin: 10ex -5px; 。

Emmet has a few aliases for commonly used values:

常用单位别名：

You can use aliases instead of full units:

Emmet supports hex color values, like this: c#3 → color: #333; . The # sign is a value separator so you don’t need to use hyphen to separate it. For example, bd5#0s expands to border: 5px #000 solid : the # sign separates color from 5 and since s (alias to solid ) is not a hexadecimal character, it can be used without - value separator.

Emmet 支持 16 进制颜色值，例如： c#3 → color: #333; 。 # 是值分隔符，所以不需要连字符。例如 bd5#0s 展开为 border: 5px #000 solid ， # 将颜色值与 5 隔开，既然 s ( solid 的别名) 不是 16 进制字符，就不需要用连字符。

You can write one, two, three or six characters as color value:

可以写 1 个， 2 个，3 个或 6 个字符作为颜色值:

Some CSS properties are defined as unit-less , e.g. no unit suffix will be outputted: lh2 → line-height: 2; , fw400 → font-weight: 400; .

有些 CSS 属性无单位。例如： lh2 → line-height: 2; , fw400 → font-weight: 400;

These values are: 'z-index , line-height , opacity and font-weight but you can override them with css.unitlessProperties preferences.

这些属性是： 'z-index , line-height , opacity 和 font-weight 。可以用选项 css.unitlessProperties 配置。

You can add ! suffix at the end of any CSS abbreviation to get !important value:

在任意 CSS 缩写后面添加 ! ，将得到 !important 值：

p!+m10e!

...will produce

padding:  !important;
margin: 10em !important;