Javascript 向html添加静态内容表

现在我想将“目录”添加到help.html的右侧，以便用户可以轻松访问help.html中的适当位置

=====          ====
tag1           tag2
=====          ====
--------------------
  help.html 

  Intro
    some intro.
  basics 
    some basic info.
   and more contents
--------------------

========
tag1 tag2
=====          ====
--------------------
help.html Intro可以通过CSS使用
位置：fixed
属性轻松完成：

=====          ====
tag1           tag2
=====          ====
--------------------
help.html      Intro <----|
               basics <---| new thing I would like to add
               topic3 <---|
  Intro
    some intro
  basics 
    some basic info.
   and more contents
--------------------

请参见我的演示：

=====          ====
tag1           tag2
=====          ====
--------------------
help.html      Intro <----|
               basics <---| new thing I would like to add
               topic3 <---|
  Intro
    some intro
  basics 
    some basic info.
   and more contents
--------------------

div.table-of-contents {
    position: fixed;

    right: 30px;
    top: 30px;
}