css做一些简单的计算_css简单运算

用 counter-reset，结合counter-increment和content,可以做一些简单的计算。

counter-reset属性创建或重置一个或多个计数器。

counter-increment 属性设置某个选取器每次出现的计数器增量。默认增量是 1。

counter()插入计数器。只能被使用在content属性上。如果想重复多次计数器可以使用 counters()

例如如下图：

<!-- html -->
<div class="languages">  
  <input id="c" type="checkbox"><label for="c">C</label>
  <input id="C++" type="checkbox"><label for="C++">C++</label>
  <input id="C#" type="checkbox"><label for="C#">C#</label>
  <input id="Java" type="checkbox"><label for="Java">Java</label>
  <input id="JavaScript" type="checkbox"><label for="JavaScript">JavaScript</label>
  <input id="PHP" type="checkbox"><label for="PHP">PHP</label>
  <input id="Python" type="checkbox"><label for="Python">Python</label>
  <input id="Ruby" type="checkbox"><label for="Ruby">Ruby</label>
</div>  
<p class="total">  
  Total selected:
</p>  
 
.languages {
  counter-reset: characters;
}
input:checked {  
  counter-increment: characters;
}
.total:after {
  content: counter(characters);
} 

注：characters 是自定义的。

还可以做计算：

<!-- html -->
<div class="numbers">  
  <input id="one" type="checkbox"><label for="one">1</label>
  <input id="two" type="checkbox"><label for="two">2</label>
  <input id="three" type="checkbox"><label for="three">3</label>
  <input id="four" type="checkbox"><label for="four">4</label>
  <input id="five" type="checkbox"><label for="five">5</label>
  <input id="one-hundred" type="checkbox"><label for="one-hundred">100</label>
</div>  
<p class="sum">  
  Sum 
</p>  
 
.numbers {
  counter-reset: sum;
}
 
#one:checked { counter-increment: sum 1; }
#two:checked { counter-increment: sum 2; }
#three:checked { counter-increment: sum 3; }
#four:checked { counter-increment: sum 4; }
#five:checked { counter-increment: sum 5; }
#one-hundred:checked { counter-increment: sum 100; }
 
.sum::after {
  content: '= ' counter(sum);
}