How do I create multiple unit_price * quantity and get value in total_price using forloop in PHP

<table class="table table-striped table-sm" data-maxrow="10" data-minrow="1">
<thead>
   <tr>
    <th class="bg-light"><label for="item_testname_id"><?php print_lang('item_testname_id'); ?></label></th>
    <th class="bg-light"><label for="unit_price"><?php print_lang('unit_price'); ?></label></th>
          <th class="bg-light"><label for="quantity"><?php print_lang('quantity'); ?></label></th>
          <th class="bg-light"><label for="total_price"><?php print_lang('total_price'); ?></label></th>
          <th></th>
      </tr>
  </thead>
  <tbody>
			//here is using forloop function create dynamic table row
      <?php 
      for( $row = 1; $row <= 1; $row++ ){

      ?>
    <tr class="input-row">
     <td>
      <div id="ctrl-item_testname_id-row<?php echo $row; ?>-holder" class="">
          <select required=""  id="ctrl-item_testname_id-row<?php echo $row; ?>" data-load-select-options="unit_price" name="row<?php echo $row ?>[item_testname_id]"  placeholder="<?php print_lang('select_a_value_'); ?>"    class="custom-select" >
              <option value=""><?php print_lang('select_a_value_'); ?></option>
              <?php 
              $item_testname_id_options = $comp_model -> pat_direct_billing_list_item_testname_id_option_list();
              if(!empty($item_testname_id_options)){
              foreach($item_testname_id_options as $option){
              $value = (!empty($option['value']) ? $option['value'] : null);
              $label = (!empty($option['label']) ? $option['label'] : $value);
              $selected = $this->set_field_selected('item_testname_id',$value, "");
              ?>
              <option <?php echo $selected; ?> value="<?php echo $value; ?>">
                  <?php echo $label; ?>
              </option>
              <?php
              }
              }
              ?>
          </select>
      </div>
       </td>
       <td>
        <div id="ctrl-unit_price-row<?php echo $row; ?>-holder" class="">
            <select required=""  id="ctrl-unit_price-row<?php echo $row; ?>" data-load-path="<?php print_link('api/json/pat_direct_billing_list_unit_price_option_list') ?>" name="row<?php echo $row ?>[unit_price]"  placeholder="<?php print_lang('select_a_value_'); ?>"    class="custom-select" >
                <option value=""><?php print_lang('select_a_value_'); ?></option>
            </select>
        </div>
       </td>
       <td>
		<div id="ctrl-quantity-row<?php echo $row; ?>-holder" class="">
           <input id="ctrl-quantity-row<?php echo $row; ?>"  value="<?php  echo $this->set_field_value('quantity',"1", $row); ?>" type="text" placeholder="<?php print_lang('enter_quantity'); ?>"  required="" name="row<?php echo $row ?>[quantity]"  class="form-control " />
        </div>
       </td>
       <td>
           <div id="ctrl-total_price-row<?php echo $row; ?>-holder" class="">
               <input id="ctrl-total_price-row<?php echo $row; ?>"  value="<?php  echo $this->set_field_value('total_price',"", $row); ?>" type="text" placeholder="<?php print_lang('enter_total_price'); ?>"  required="" name="row<?php echo $row ?>[total_price]"  class="form-control " />
               </div>
           </td>
           <th class="text-center">
//here is delete button
               <button type="button" class="close btn-remove-table-row">×</button>
           </th>
      </tr>
           <?php 
           }
           ?>//end forloop 
          </tbody>
 <tfoot>
     <tr>
       <th colspan="100" class="text-right">
           <?php $template_id = "table-row-" . random_str(); ?>
           <button type="button" data-template="#<?php echo $template_id ?>" class="btn btn-sm btn-light btn-add-table-row">class="fa fa-plus"></button>
       </th>
     </tr>
 </tfoot>
</table>

total=0;
for($row = 1; $row <= 1; $row++){
  total_price = document.getElementById('ctrl-total_price-row'+$row).value;
 quantity = document.getElementById('ctrl-quantity-row'+$row).value;
  
  r =(total_price*quantity);
  total+=r;
  document.getElementById('ctrl-total_price-row'+$row).innerHTML = r +;
}