JSFiddle - React, Tailwind, and code Playground

HTML

<script src="http://cdnjs.cloudflare.com/ajax/libs/json2/20140204/json2.js"></script>
<table>
  <tr>
      <th>name</th>
      <th>address</th>
      <th>city</th>
  </tr>
  <tr>
      <td data-attr="name" class="toJson">amy</td>
      <td data-attr="address" class="toJson">123 El St.</td>
      <td data-attr="city" class="toJson">Rossberg</td>
  </tr>

  <tr>
      <td data-attr="name" class="toJson">john</td>
      <td data-attr="address" class="toJson">232 Rosary Rd.</td>
      <td data-attr="city" class="toJson">Newberg</td>
  </tr>
</table>

JavaScript

var counter = 1;
var mainArray = [];
var subArray = new Object();

$('.toJson').each(function(){
    var col = $(this);
     subArray[col.data('attr')] = col.html();
    
    if(counter == 3)
    {
        mainArray.push(subArray);
        subArray = new Object();
        counter = 0;
    }
    counter++;
});

alert(JSON.stringify(mainArray));