留出CSS块的最后一个分号 [英] Leaving out the last semicolon of a CSS block

问题描述

有关这方面的几个问题：

• 这是好习惯吗？




• 对于最后一个功能，这是一样的吗？
在Javascript（/ jQuery）？

我的意思是这样的东西：

  #myElement {
 position：absolute; 
 top：0; 
 left：0 
} 
  

解决方案

是否是好的习惯？

分号。这是纯粹是因为在添加更多样式时很容易忽略，特别是如果你在一个团队中工作：

想象一下你开始：

  .foo {
 background-color：＃F00; 
 color：＃000<  - 缺少分号
} 
  

然后有人添加了一些样式：

  .foo {
 background-color：＃F00; 
 color：＃000<  - 缺少分号
 width：30px; 
 z-index：100; 
} 
  

突然，其​​他开发人员浪费时间知道为什么他们 width 声明不工作（或更糟的是，没有注意到它不工作）。

在大规模上，会产生更好的加载时间吗？ strong>

最明确的是，对于每个块，你会保存几个字节。这些加起来，特别是对于大样式表。不要担心这些性能增益本身，最好使用CSS Compressor，例如 YUI Compressor 来自动删除

不，它是安全的，因为浏览器正确实现这部分规范。 CSS2规范定义了一个声明：

一个声明是空的，或者是一个属性名称，后跟一个冒号（:)，后跟一个属性值。

更重要的是：

...多个声明可以组织成分号（;）分隔的组。

这意味着; 用于分隔多个声明，但不需要它们来终止它们。

Javascript？

JavaScript是一个完全不同的规格的完全不同的野兽。这个特定问题已经深入地回答了很多次堆栈溢出。

Couple of questions concerning this:

• Is it good practice?
• Will it, on a large scale, result in better load times?
• Can it result in browsers 'breaking'?
• Is the same true for the last function in Javascript (/jQuery)?

What I mean is stuff like this:

#myElement {
  position: absolute;
  top: 0;
  left: 0
}

解决方案

Is it good practice?

It's not good practice to manually exclude semi-colons. This is purely because it's easy to overlook when adding more styles, especially if you're working in a team:

Imagine you start with:

.foo {
    background-color: #F00;
    color: #000             <-- missing semi-colon
}

And then someone adds some styles:

.foo {
    background-color: #F00;
    color: #000             <-- missing semi-colon
    width: 30px;
    z-index: 100;
}

Suddenly the other developer is wasting time figuring out why their width declaration isn't working (or worse yet, doesn't notice that it's not working). It's safer to leave the semi-colons in

Will it, on a large scale, result in better load times?

Most definitely, for every block, you'd save a couple bytes. These add up, especially for large style sheets. Instead of worrying about these performance gains yourself, it's better to use a CSS Compressor, such as the YUI Compressor to automatically remove the ending semi-colons for you.

Can it result in browsers 'breaking'?

No, it's safe, as browsers implement this part of the specification correctly. The CSS2 specification defines a declaration thusly:

A declaration is either empty or consists of a property name, followed by a colon (:), followed by a property value.

More importantly:

...multiple declarations for the same selector may be organized into semicolon (;) separated groups.

This means that ; is used to separate multiple declarations, but are not needed to terminate them.

Is the same true for the last function in Javascript?

JavaScript is a whole different beast with a completely different specification. This particular question has been answered in depth many times before on Stack Overflow.

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