can jquery support a menu sending files to 3 different DIVs on the same page

can jquery support a menu sending files to 3 different DIVs on the same page

I am trying to update from frames to flexbox.  Now i am trying to use jquery.  I have succesfully been able to load  the menu from the first div into the second.  But sending files from the second div to load into the third nothing I try works. The first div holds a master menu. the second holds a submenu.  The thrid div is for viewing files.  Id like to actually have a fourth DIV  for viewing files as well.  This is a large educational tool I build in frames.  With the target command I have no problem sending into the different frames.  How do i  accomplish this in jquery? 

This also is running off-line.  It has the ability to write notes and view articles vocab etc that a student will need in his or her studies.  Its a hefty size of 64gb due to support learning files.  The index/menus are about 2gb as its for every subject (LA/ELL has about 75% of these files).  Began in html 2.0 and now switiching to html 5 flexbox

Am I "barking up the wrong tree" (looking in the wrong place {JQUERY} for an answer)?

Heres  what I have tried so far
writing the jquery code inside both the container document and the sub-menu external file that Jquery The home page where everything loads has the main menu inside it and it loads the external submenu with no problem.  But when I click on the submenu it says the file is not found and nothing shows in the 3rd div on the home page.  IF I change the submenu to target="_blank" when I click the submenu inside the home page it opens the doc in a new tab with no problems.  It then finds the page. 

My goal is to have the menu open in a third div something the student needs to read and the if possible open the notes/quiz questions vocab etc in the fourth div so that what is read is next to the contenteditable page  in  div 4.  

This is my flexbox home page
<style type="text/css">

.row1 {
  display: -webkit-flex;
  display: -moz-flex;
  display: -ms-flexbox;
  display: -ms-flex;
  display: flex;
  flex-direction: row;
  justify-content: flex-start;
  align-items: flex-start;
  flex-wrap: nowrap;
  min-height: calc(70vh); /* set min container height to viewport height */
}
.row2 {
  display: -webkit-flex;
  display: -moz-flex;
  display: -ms-flexbox;
  display: -ms-flex;
  display: flex;
  flex-direction: row;
  justify-content: flex-start;
  align-items: flex-start;
  flex-wrap: nowrap;
  min-height: calc(30vh); /* set min container height to viewport height */
}


.col-1 {
  flex: 0 1 30%;
  background: beige;
  border: 1px solid black;
  font-size: 2em;
  padding: 4px;
  overflow: hidden;
  overflow: scroll;
  box-sizing: border-box;
  min-height: calc(70vh); /* set min container height to viewport height */
}

.col-2 {
  display: flex;
  flex: 0 1 auto;
  margin-left: auto;
  background: ;
  border: 1px solid black;
  padding: 4px; 
  text-overflow: ellipsis;
  max-height: 70%;
  overflow: hidden;
  box-sizing: border-box;
  min-height: calc(70vh); /* set min container height to viewport height */
 
 
}
.col-3 {
  flex: 0 1 22%;
  background: beige;
  border: 1px solid black;
  padding: 4px;
  overflow: hidden;
  overflow: scroll;
  box-sizing: border-box;
  min-height: calc(30vh); /* set min container height to viewport height */
}
.col-4 {
  flex: 0 1 6%;
  margin-left: auto;
  background: #eee;
  border: 1px solid black;
  padding: 4px;
  overflow: hidden;
  overflow: scroll;
  box-sizing: border-box;
  min-height: calc(30vh); /* set min container height to viewport height */
}
.col-5 {
  flex: 0 1 21%; 
  margin-left: auto;
  background: #eee;
  border: 1px solid black;
  padding: 4px;
  overflow: hidden;
  box-sizing: border-box;
  min-height: calc(30vh); /* set min container height to viewport height */
  min-width: calc(10vw);
}

body {width: 100%; height: 100%; margin: 0; padding: 0}

iframe {
    display: block;
    overflow: scroll;
    overflow: hidden;  
      max-width: 100%;
    max-height: 435px;
    margin: 0 auto;
    border: 0px solid black;}
   
li.en24-N
{  color: black;
    font-family: arial, Sans-serif;
    font-size: 24pt;}
    p
{    color: black;
    font-family: arial, Sans-serif;
    font-size: 12pt;}
</style>
</head>
<body>



 
<section class="row2">
    <div class="col-3" id="index-A">
    </div>
    <div class="col-4" id="menu-A">
    </div>
    <div class="col-3" id="index-B">
    </div>
    <div class="col-4" id="menu-B">
    </div>
    <div class="col-3" id="index-C">
    </div>
    <div class="col-4" id="menu-C">
    </div>
    <div class="col-5" id="toc">
    </div>
 </section>

<section class="row1">
    <div class="col-1" id="file-A">
    </div>
    <div class="col-1" id="file-B">
    </div>
    <div class="col-1" id="file-C">
    </div>
    <div class="col-2" id="contents-menu">
    <iframe src="0_netbook_loy__contents.html" scrolling="auto" frameborder="0"></ifraame>  
    </div>
 </section>

an example of a submenu is

<body>

<div class="treehouse">

<ul>
<li><input type="checkbox" id="item-6-1" /><label for="item-6-1" class="green3"><span xml:lang="en" lang="en">A</span></label>
    <ul>
        <li><a href="_A-0/AI-eng__a-01__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-02__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-03__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-04__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-05__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-06__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-07__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-08__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-09__idx-A.html" target="content" class="green8"> A </a>
        </li><li><a href="_A-0/AI-eng__a-10__idx-A.html" target="content" class="green8"> A </a>
        </li>             
    </ul> 
   
   
   
</li><li><input type="checkbox" id="item-6-26" /><label for="item-6-26" class="green3"><span xml:lang="en" lang="en">Z</span></label>
    <ul>
        <li><a href="_Z-0/AI-eng__z-01__idx-A.html" target="content" class="green8"> Z </a>
        </li><li><a href="_Z-0/AI-eng__z-02__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-03__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-04__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-05__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-06__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-07__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-08__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-09__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li><li><a href="_Z-0/AI-eng__z-10__idx-A.html" target="content" class="green8"> Go </a>  Z
        </li>     
    </ul>   

</li>
</ul>


</li>
</ul>
</div>

I know the target does not work in jquery.  If it did Id have this solved! 
I am using the script commands suggested from this website. 
<script type='text/javascript' src='jquery-3.3.1.js'></script>
<script type="text/javascript" src="lib/jquery-1.js"></script>
    <script type="text/javascript">
    $(function(){
        $('#nav ul li a').click(function(e) {
              $('#index').hide().load( $(this).attr('href') , function(){
                     $('#index').show()
              })
              return false
        })
    })
    </script>

any suggestions?