append div inside th

HTML

<table id="T_3bac276a_15f8_11ea_b73d_475809f3cfcd" >
   <thead>
      <tr>
         <th class="blank level0" ></th>
         <th class="col_heading level0 col0" > a</th>
         <th class="col_heading level0 col1" >b</th>
         <th class="col_heading level0 col2" >c</th>
         <th class="col_heading level0 col3" >d</th>
      </tr>
   </thead>
   <tbody>
      <tr>
         <th id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdlevel0_row0" class="row_heading level0 row0" > 0
         </th>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow0_col0" class="data row0 col0" >1</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow0_col1" class="data row0 col1" >x</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow0_col2" class="data row0 col2" >0</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow0_col3" class="data row0 col3" >0.0106405</td>
      </tr>
      <tr>
         <th id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdlevel0_row1" class="row_heading level0 row1" >1</th>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow1_col0" class="data row1 col0" >2</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow1_col1" class="data row1 col1" >y</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow1_col2" class="data row1 col2" >0</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow1_col3" class="data row1 col3" >0.00423519</td>
      </tr>
      <tr>
         <th id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdlevel0_row2" class="row_heading level0 row2" >2</th>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow2_col0" class="data row2 col0" >3</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow2_col1" class="data row2 col1" >z</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow2_col2" class="data row2 col2" >0</td>
         <td id="T_3bac276a_15f8_11ea_b73d_475809f3cfcdrow2_col3" class="data row2 col3" >0.0071003</td>
      </tr>
   </tbody>
</table>

CSS

.col_heading.level0.col2 {
  position: relative;
  display: inline-block;
}

.col_heading.level0.col2 .tooltiptext {
  visibility: hidden;
  width: 120px;
  background-color: black;
  color: #fff;
  text-align: center;
  border-radius: 6px;
  padding: 5px 0;

  /* Position the tooltip */
  position: absolute;
  z-index: 1;
}

.col_heading.level0.col2:hover .tooltiptext {
  visibility: visible;
}

#T_3bac276a_15f8_11ea_b73d_475809f3cfcd
{
	position:absolute;
    

}

JavaScript

$('.col_heading.level0.col2').prepend('<div class="tooltiptext">This is it.</div>')