JSFiddle - React, Tailwind, and code Playground

HTML

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.6/css/bootstrap.min.css">
<button id="clone">
Clone Row
</button>
<div id="rows">
  <div class="row" id="rowsec">
    <div class="col-md-2 col-sm-3 col-lg-1 nopadding">
      <input class="form-control input-sm nopadding" type="text" placeholder="Floor" maxlength="4" name="floor">
    </div>
    <div class="col-md-2 col-sm-3 col-lg-1 nopadding">
      <input class="form-control input-sm nopadding" type="text" placeholder="Length" maxlength="4" name="length">
    </div>
    <div class="col-md-2 col-sm-3 col-lg-1 nopadding">
      <input class="form-control input-sm nopadding" type="text" placeholder="Width" maxlength="4" name="width">
    </div>
    <div class="col-md-2 col-sm-3 col-lg-1 nopadding">
      <input class="form-control input-sm nopadding" type="text" placeholder="Sqft" maxlength="4" name="sqft">
    </div>
  </div>
</div>

JavaScript

/**
 * Create a clone of the row template and add it to the #rows container.
 */
function cloneRow(){
    //Clone the entire row
    var $clone = $('#rowsec').clone();

    //Clear the input values.  Customize this if needed
    $clone.find('input').val(0);

    //Remove the ID so there's only one in the dom.
    $clone.removeAttr('id');

    //Add it to the rows container
    $('#rows').append($clone);
}

/**
 * Handle a change event.  Within the function `this` refers to the input that changed
 * We can use jQuery to find the other inputs based on the changed input
 * then run the calculations.
 */
function compute(){
    var $row = $(this).closest('.row');
    var $floor = $row.find('[name=floor]');
    var $length = $row.find('[name=length]');
    var $width = $row.find('[name=width]');
    var $sqft = $row.find('[name=sqft]');

    //Do your calculations
    $sqft.val($length.val() * $width.val());
}

//Clone row when button is clicked
$('#clone').click(cloneRow);

//Handle change events in each row
$('#rows').on('change', 'input', compute);