CSS伪元素计数器：可以增加字母“ a”，“ b”，“ c”等而不是数字吗？

Question

您可以使用以下代码来增加伪元素中的数字。

H1:before {
    content: "Chapter " counter(chapter) ". ";
    counter-increment: chapter;  /* Add 1 to chapter */
}
H1 {
    counter-reset: section;      /* Set section to 0 */
}
H2:before {
    content: counter(chapter) "." counter(section) " ";
    counter-increment: section;
}

有没有一种方法可以使用相同的代码来递增字母，例如“ a”，“ b”，“ c”等？

谢谢！

Answer 1

是的，的第二个参数counter()定义了使用的计数器的类型，例如list-style-type来自常规ul或的ol；例如：

content: counter(chapter, lower-alpha);



ul {

  counter-reset: listStyle;

}

ul li {

  margin-left: 1em;

  counter-increment: listStyle;

}

ul li::before {

  margin-right: 1em;

  content: counter(listStyle, lower-alpha);

}


<ul>

  <li>one</li>

  <li>two</li>

  <li>three</li>

</ul>

其他包括：decimal，decimal-leading-zero，lower-roman，upper-roman，lower- greek，lower-latin，upper-latin，armenian，georgian，lower-alpha，upper- alpha。

由于上面的样式列表似乎有所更新，我选择添加一个代码段，该代码段使用户可以从（当前）可用选项中进行选择，以及一个“输出”区域，以显示如何在CSS生成内容中使用该样式：

let select = document.querySelector('select'),

  output = document.querySelector('#currentCounter'),

  changeEvent = new Event('change');



select.addEventListener('change', function() {

  document.body.style.setProperty('--listStyleType', this.value);

  output.textContent = this.value;

});



select.dispatchEvent(changeEvent);


body {

  --listStyleType: decimal;

}



ul {

  counter-reset: listStyle;

  columns: 2;

  margin-top: 0.5em;

  list-style-type: none;

}



ul li {

  counter-increment: listStyle;

}



ul li::before {

  content: counter(listStyle, var(--listStyleType));

  display: inline-block;

  margin-right: 0.5em;

  width: 1.5em;

  height: 1.5em;

  line-height: 2em;

  text-align: center;

}



code {

  display: block;

  white-space: pre-wrap;

  width: 80%;

  box-sizing: border-box;

  margin: 1em auto;

  padding: 0.5em;

  box-shadow: 0 0 0 3px limegreen;

}



code::after {

  content: '\A';

}



#currentCounter {

  color: #f90;

}


<label for="counterChoice">Please select a CSS counter:</label>

<select id="counterChoice">

  <option value="arabic-indic">arabic-indic</option>

  <option value="armenian">armenian</option>

  <option value="bengali">bengali</option>

  <option value="cambodian">cambodian</option>

  <option value="circle">circle</option>

  <option value="cjk-decimal">cjk-decimal</option>

  <option value="cjk-earthly-branch">cjk-earthly-branch</option>

  <option value="cjk-heavenly-stem">cjk-heavenly-stem</option>

  <option value="decimal">decimal</option>

  <option value="decimal-leading-zero">decimal-leading-zero</option>

  <option value="devanagari">devanagari</option>

  <option value="disc">disc</option>

  <option value="disclosure-closed">disclosure-closed</option>

  <option value="disclosure-open">disclosure-open</option>

  <option value="ethiopic-numeric">ethiopic-numeric</option>

  <option value="georgian">georgian</option>

  <option value="gujarati">gujarati</option>

  <option value="gurmukhi">gurmukhi</option>

  <option value="hebrew">hebrew</option>

  <option value="hiragana">hiragana</option>

  <option value="hiragana-iroha">hiragana-iroha</option>

  <option value="japanese-formal">japanese-formal</option>

  <option value="japanese-informal">japanese-informal</option>

  <option value="kannada">kannada</option>

  <option value="katakana">katakana</option>

  <option value="katakana-iroha">katakana-iroha</option>

  <option value="khmer">khmer</option>

  <option value="korean-hangul-formal">korean-hangul-formal</option>

  <option value="korean-hanja-formal">korean-hanja-formal</option>

  <option value="korean-hanja-informal">korean-hanja-informal</option>

  <option value="lao">lao</option>

  <option value="lower-alpha">lower-alpha</option>

  <option value="lower-alpha">lower-alpha</option>

  <option value="lower-armenian">lower-armenian</option>

  <option value="lower-greek">lower-greek</option>

  <option value="lower-latin">lower-latin</option>

  <option value="lower-roman">lower-roman</option>

  <option value="malayalam">malayalam</option>

  <option value="mongolian">mongolian</option>

  <option value="myanmar">myanmar</option>

  <option value="oriya">oriya</option>

  <option value="persian">persian</option>

  <option value="simp-chinese-formal">simp-chinese-formal</option>

  <option value="simp-chinese-informal">simp-chinese-informal</option>

  <option value="square">square</option>

  <option value="tamil">tamil</option>

  <option value="telugu">telugu</option>

  <option value="thai">thai</option>

  <option value="tibetan">tibetan</option>

  <option value="trad-chinese-formal">trad-chinese-formal</option>

  <option value="trad-chinese-informal">trad-chinese-informal</option>

  <option value="upper-alpha">upper-alpha</option>

  <option value="upper-armenian">upper-armenian</option>

  <option value="upper-latin">upper-latin</option>

  <option value="upper-roman">upper-roman</option>

</select>

<ul>

  <li>one</li>

  <li>two</li>

  <li>three</li>

  <li>four</li>

  <li>five</li>

  <li>six</li>

  <li>seven</li>

  <li>eight</li>

  <li>nine</li>

  <li>ten</li>

</ul>



<code>

  li::before {

    content: counter(&lt;counterName&gt;, <span id="currentCounter"></span>)

  }

</code>

当前可用（截至2017年2月27日）：

• arabic-indic
• armenian
• bengali
• cambodian
• circle
• cjk-decimal
• cjk-earthly-branch
• cjk-heavenly-stem
• decimal
• decimal-leading-zero
• devanagari
• disc
• disclosure-closed
• disclosure-open
• ethiopic-numeric
• georgian
• gujarati
• gurmukhi
• hebrew
• hiragana
• hiragana-iroha
• japanese-formal
• japanese-informal
• kannada
• katakana
• katakana-iroha
• khmer
• korean-hangul-formal
• korean-hanja-formal
• korean-hanja-informal
• lao
• lower-alpha
• lower-alpha
• lower-armenian
• lower-greek
• lower-latin
• lower-roman
• malayalam
• mongolian
• myanmar
• oriya
• persian
• simp-chinese-formal
• simp-chinese-informal
• square
• tamil
• telugu
• thai
• tibetan
• trad-chinese-formal
• trad-chinese-informal
• upper-alpha
• upper-armenian
• upper-latin
• upper-roman