文章或博客自动生成章节目录索引(支持三级)的实现代码

<script language="javascript" type="text/javascript">
//生成目录索引列表
function GenerateContentList()
{
  var jquery_h3_list = $('#cnblogs_post_body h3');//如果你的章节标题不是h3,只需要将这里的h3换掉即可
  if(jquery_h3_list.length>0)
  {
    var content = '<a name="_labelTop"></a>';
    content  += '<div id="navCategory">';
    content  += '<p style="font-size:18px"><b>阅读目录</b></p>';
    content  += '<ul>';
    for(var i =0;i<jquery_h3_list.length;i++)
    {
      var go_to_top = '<div style="text-align: right"><a href="#_labelTop" rel="external nofollow" rel="external nofollow" >回到顶部</a><a name="_label' + i + '"></a></div>';
      $(jquery_h3_list[i]).before(go_to_top);
      var li_content = '<li><a href="#_label' + i + '" rel="external nofollow" rel="external nofollow" >' + $(jquery_h3_list[i]).text() + '</a></li>';
      content += li_content;
    }
    content  += '</ul>';
    content  += '</div>';
    if($('#cnblogs_post_body').length != 0 )
    {
      $($('#cnblogs_post_body')[0]).prepend(content);
    }
  }  
}
GenerateContentList();
</script>

<script language="javascript" type="text/javascript">
//生成目录索引列表
function GenerateContentList()
{
  var jquery_h1_list = $('#cnblogs_post_body h1');
  if (jquery_h1_list.length == 0) { return; }
  if ($('#cnblogs_post_body').length == 0) { return; }

  var content = '<a name="_labelTop"></a>';
  content  += '<div id="navCategory">';
  content  += '<p style="font-size:18px"><b>阅读目录(Content)</b></p>';
  // 一级目录 start
  content += '<ul class="first_class_ul">';

  for (var i = 0; i < jquery_h1_list.length; i++)
  {
    var go_to_top = '<div style="text-align: right"><a href="#_labelTop" rel="external nofollow" rel="external nofollow" >回到顶部(go to top)</a><a name="_label' + i + '"></a></div>';
    $(jquery_h1_list[i]).before(go_to_top);

    // 一级目录的一条
    var li_content = '<li><a href="#_label' + i + '" rel="external nofollow" rel="external nofollow" >' + $(jquery_h1_list[i]).text() + '</a></li>';

    var nextH1Index = i + 1;
    if (nextH1Index == jquery_h1_list.length) { nextH1Index = 0; }
    var jquery_h2_list = $(jquery_h1_list[i]).nextUntil(jquery_h1_list[nextH1Index], "h2");
    // 二级目录 start
    if (jquery_h2_list.length > 0)
    {
      //li_content +='<ul style="list-style-type:none; text-align: left; margin:2px 2px;">';
      li_content += '<ul class="second_class_ul">';
    }
    for (var j = 0; j < jquery_h2_list.length; j++)
    {
      var go_to_top2 = '<div style="text-align: right"><a name="_lab2_'+ i + '_' + j + '"></a></div>';
      $(jquery_h2_list[j]).before(go_to_top2);
      // 二级目录的一条
      li_content +='<li><a href="#_lab2_'+ i +'_' + j + '" rel="external nofollow" >' + $(jquery_h2_list[j]).text() + '</a></li>';

      var nextH2Index = j + 1;
      var next;
      if (nextH2Index == jquery_h2_list.length) 
      {
        if (i + 1 == jquery_h1_list.length)
        {
          next = jquery_h1_list[0];
        }
        else
        {
          next = jquery_h1_list[i + 1];
        }
      }
      else
      {
        next = jquery_h2_list[nextH2Index];
      }
      var jquery_h3_list = $(jquery_h2_list[j]).nextUntil(next, "h3");
      // 三级目录 start
      if (jquery_h3_list.length > 0)
      {
        li_content += '<ul class="third_class_ul">';
      }
      
      for (var k = 0; k < jquery_h3_list.length; k++)
      {
        var go_to_third_Content = '<div style="text-align: right"><a name="_label3_' + i + '_' + j + '_' + k + '"></a></div>';
        $(jquery_h3_list[k]).before(go_to_third_Content);
        // 三级目录的一条
        li_content += '<li><a href="#_label3_' + i + '_' + j + '_' + k + '" rel="external nofollow" >' + $(jquery_h3_list[k]).text() + '</a></li>';
      }
      
      if (jquery_h3_list.length > 0)
      {
        li_content += '</ul>';
      }
      li_content += '</li>';
      // 三级目录 end
    }
    if (jquery_h2_list.length > 0)
    {
      li_content +='</ul>';
    }
    li_content +='</li>';
    // 二级目录 end

    content += li_content;
  }
  // 一级目录 end
  content += '</ul>';
  content += '</div>';

  $($('#cnblogs_post_body')[0]).prepend(content);
}

GenerateContentList();
</script>
levels of contents

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <style>
    * {
      margin: 0;
      padding: 0;
      word-break: break-all;
    }
    #toc {
      width: 200px;
      position: fixed;
      left: 0;
      top: 0;
    }
    #toc a.active {
      color: red;
    }
    #content {
      margin-left: 200px;
    }
  </style>
  <script src="/UploadFiles/2021-04-02/jquery.min.js">

具体的使用可以参考下面的文章。