21

I have a list ul>li*5 (not always the same amount). I set a counter for which I get:

1 2 3 4 5

li:nth-child(n):before {
  counter-increment: skill;
  content: counter(skill);
  color: white;
}

The Question Can I use the counter(skill) inside a calc() or can I add units to it px em rem % ms s

I have tried:

transition: all 250ms linear #{counter(skill)} * 1s;
transition: all 250ms linear counter(skill) * 1s;

I want to have the delay increased for example:

li 1s delay
li 2s delay
li 3s delay
li 4s delay
li Xs delay
4

2 回答 2

46

问题我可以在 calc() 中使用计数器（技能）吗

不，你不能。

该calc函数不允许将counter函数用作其组件。从这里的规格 - https://www.w3.org/TR/css3-values/#calc-notation：

表达式的组成部分 calc()可以是文字值 attr()或 calc() 表达式。

对此有很多要求，但总是被拒绝。根本原因似乎是该counter()函数表示（输出） a <string>，因此不能直接用于calc. 此外，对于浏览器来说，计数器被认为是非常昂贵的。

参考： https ://lists.w3.org/Archives/Public/www-style/2016Aug/0082.html

但是，有人提议添加一个counter-value()函数，该函数将返回整数值并可以在calc. 请参阅此处：https ://drafts.c​​sswg.org/css-lists-3/#counter-functions （向下滚动以查看第 4 期）。

所以到目前为止，你不能使用counterinside ofcalc并且counter-value还不存在。

于 2017-04-21T10:39:38.497 回答
15

这不一定是一个优雅的解决方案，但您可以使用 nth-child 或使用 css 变量来解决它。下面的代码，或在这里查看：https ://codepen.io/goodship11/pen/XBVeez

第n个孩子版本：

li { 
  opacity: 0; 
  padding: 5px 0 5px 5px;
  list-style: none;
  background-color: rgba(200,50,255,.2);
  display: block;
  width: 20%;
  height: 10%;
}
li:nth-child(even) { background-color: rgba(200,50,255,.5); }

@keyframes fade { 0% { opacity: 0; } 100% { opacity: 1; } }

li { animation: fade 1.5s ease-in forwards; }

/* Since you're doing an animation, chances our the number 
of elements will be small, so you can just pre-define for however 
many versions using nth-child. This wouldn't work for use cases 
where, for example, you want a percentage of the whole instead 
of a fixed number */

li:nth-child(1) { animation-delay: 1s; }
li:nth-child(2) { animation-delay: 2s; }
li:nth-child(3) { animation-delay: 3s; }
li:nth-child(4) { animation-delay: 4s; }
li:nth-child(5) { animation-delay: 5s; }
li:nth-child(6) { animation-delay: 6s; }
li:nth-child(7) { animation-delay: 7s; }
li:nth-child(8) { animation-delay: 8s; }
<ul>
  <li>Thing 1</li>
  <li>Thing 2</li>
  <li>Thing 3</li>
  <li>Thing 4</li>
  <li>Thing 5</li>
</ul>

CSS 变量版本：

li { 
  opacity: 0; 
  padding: 5px 0 5px 5px;
  list-style: none;
  background-color: rgba(200,50,255,var(--fader));
  display: block;
  width: 20%;
  height: 10%;
}
@keyframes fade { 0% { opacity: 0; } 100% { opacity: 1; } }

li { animation: fade 1.5s ease-in forwards; }

/* Below is an alternative approach using the same variable 
from the opacity. I added in a scaling factor to show how you 
can use one variable for multiple things in cases like this.  */ 

:root {--factor: .5; }
li { animation-delay: calc(10s * var(--fader) * var(--factor));}
<ul>

  <!-- You can define the variable in-line, useful for in 
cases where you're writing the html manually but don't want to 
mess with the stylesheet. '--fader: .1' defines the variable 
for that instance of the li -->

  <li style="--fader: .1;">Thing 1</li>
  <li style="--fader: .2;">Thing 2</li>
  <li style="--fader: .3;">Thing 3</li>
  <li style="--fader: .4;">Thing 4</li>
  <li style="--fader: .5;">Thing 5</li>
</ul>

于 2018-07-30T14:41:32.277 回答