jQuery DataTable Server-side processing with ExpressJs. In this very basic example let's forget for a moment about filtering and ordering

app.js

baseRouter.get('/fruitsList', (req, res) => {
  /*
  DataTable when Server-side processing is true sends the data it needs in the query string as you can 
  see in the network tab of any web inspector filtering GET XHR requests.
  remember to always parse integer parameters to avoid any possible SQLinjection or XSS attack 
  (as DataTable Server-side processing documentation recommend too)
  */
  var draw = parseInt(req.query.draw);
  var start = parseInt(req.query.start);
  var length = parseInt(req.query.length);

  /*
  following function calls some REST api performing the query in the db like 
  `/api/v1/fruits?limit=${length}&offset=${start}`
  or performs some query like 
  SELECT TOP `length` name, color, description FROM fruits WHERE id >= `start`
  */
  var fruitsList = await FruitsEndpoint.getFruitsList(start, length);
  
  /*
  following function calls some REST api performing the query in the db like 
  `/api/v1/fruits/length
  or performs some query like 
  SELECT count(*) FROM fruits
  because DataTable needs it to perform pagination
  */
  var totalFruitsLength = await FruitsEndpoint.getTotalFruitsLength();
  
  var fruitsListForFrontend = {
    draw: draw,
    recordsTotal : totalFruitsLength,
    recordsFiltered : totalFruitsLength,
    data: fruitsList
  };

  res.send(fruitsListForFrontend);
  
});

fruits.html

<table id="fruitsTable">
  <thead>
    <tr>
        <th>name</th>
        <th>color</th>
        <th>description</th>
    </tr>
    </thead>
</table>

fruitsTableCreator.js

$(document).ready(

  function () {

    $('#fruitsTable').DataTable( {
        'processing': true,
        'serverSide': true,
        'ajax': '/fruitsList',
        'columns': [
          { 'data': 'name' },
          { 'data': 'color' },
          { 'data': 'description' }
        ]
    });
  }):