Datatable search based on columns - datatable

Question

I have datatables and search based on All and columns. Here everything is fine but in search dropdown selection, table is not refreshing. For ex: I selected 'Name' on dropdown and typed something on right side search textbox..it can able to search but if I select other option from dropdown in the middle of search, previous selection is showing instead refreshing the table. Below is my code.
HTML
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<script type="text/javascript" charset="utf8" src="https://cdn.datatables.net/1.10.16/js/jquery.dataTables.js"></script>
<link rel="stylesheet" type="text/css" href="https://cdn.datatables.net/1.10.16/css/jquery.dataTables.css">
<table id="example">
<thead>
<tr>
<th>Seq.</th>
<th>Name</th>
<th>Position</th>
<th>Office</th>
<th>Start date</th>
<th>Salary</th>
</tr>
</thead>
<tbody>
<tr>
<td>2</td>
<td>Tiger Nixon</td>
<td>System Architect</td>
<td>Edinburgh</td>
<td>2011/04/25</td>
<td>$320,800</td>
</tr>
<tr>
<td>22</td>
<td>Garrett Winters</td>
<td>Accountant</td>
<td>Tokyo</td>
<td>2011/07/25</td>
<td>$170,750</td>
</tr>
<tr>
<td>6</td>
<td>Ashton Cox</td>
<td>Junior Technical Author</td>
<td>San Francisco</td>
<td>2009/01/12</td>
<td>$86,000</td>
</tr>
<tr>
<td>41</td>
<td>Cedric Kelly</td>
<td>Senior Javascript Developer</td>
<td>Edinburgh</td>
<td>2012/03/29</td>
<td>$433,060</td>
</tr>
<tr>
<td>55</td>
<td>Airi Satou</td>
<td>Accountant</td>
<td>Tokyo</td>
<td>2008/11/28</td>
<td>$162,700</td>
</tr>
<tr>
<td>21</td>
<td>Brielle Williamson</td>
<td>Integration Specialist</td>
<td>New York</td>
<td>2012/12/02</td>
<td>$372,000</td>
</tr>
<tr>
<td>46</td>
<td>Herrod Chandler</td>
<td>Sales Assistant</td>
<td>San Francisco</td>
<td>2012/08/06</td>
<td>$137,500</td>
</tr>
<tr>
<td>50</td>
<td>Rhona Davidson</td>
<td>Integration Specialist</td>
<td>Tokyo</td>
<td>2010/10/14</td>
<td>$327,900</td>
</tr>
<tr>
<td>26</td>
<td>Colleen Hurst</td>
<td>Javascript Developer</td>
<td>San Francisco</td>
<td>2009/09/15</td>
<td>$205,500</td>
</tr>
<tr>
<td>18</td>
<td>Sonya Frost</td>
<td>Software Engineer</td>
<td>Edinburgh</td>
<td>2008/12/13</td>
<td>$103,600</td>
</tr>
<tr>
<td>13</td>
<td>Jena Gaines</td>
<td>Office Manager</td>
<td>London</td>
<td>2008/12/19</td>
<td>$90,560</td>
</tr>
<tr>
<td>23</td>
<td>Quinn Flynn</td>
<td>Support Lead</td>
<td>Edinburgh</td>
<td>2013/03/03</td>
<td>$342,000</td>
</tr>
<tr>
<td>14</td>
<td>Charde Marshall</td>
<td>Regional Director</td>
<td>San Francisco</td>
<td>2008/10/16</td>
<td>$470,600</td>
</tr>
<tr>
<td>12</td>
<td>Haley Kennedy</td>
<td>Senior Marketing Designer</td>
<td>London</td>
<td>2012/12/18</td>
<td>$313,500</td>
</tr>
<tr>
<td>54</td>
<td>Tatyana Fitzpatrick</td>
<td>Regional Director</td>
<td>London</td>
<td>2010/03/17</td>
<td>$385,750</td>
</tr>
<tr>
<td>37</td>
<td>Michael Silva</td>
<td>Marketing Designer</td>
<td>London</td>
<td>2012/11/27</td>
<td>$198,500</td>
</tr>
<tr>
<td>32</td>
<td>Paul Byrd</td>
<td>Chief Financial Officer (CFO)</td>
<td>New York</td>
<td>2010/06/09</td>
<td>$725,000</td>
</tr>
<tr>
<td>35</td>
<td>Gloria Little</td>
<td>Systems Administrator</td>
<td>New York</td>
<td>2009/04/10</td>
<td>$237,500</td>
</tr>
<tr>
<td>48</td>
<td>Bradley Greer</td>
<td>Software Engineer</td>
<td>London</td>
<td>2012/10/13</td>
<td>$132,000</td>
</tr>
<tr>
<td>45</td>
<td>Dai Rios</td>
<td>Personnel Lead</td>
<td>Edinburgh</td>
<td>2012/09/26</td>
<td>$217,500</td>
</tr>
<tr>
<td>17</td>
<td>Jenette Caldwell</td>
<td>Development Lead</td>
<td>New York</td>
<td>2011/09/03</td>
<td>$345,000</td>
</tr>
<tr>
<td>57</td>
<td>Yuri Berry</td>
<td>Chief Marketing Officer (CMO)</td>
<td>New York</td>
<td>2009/06/25</td>
<td>$675,000</td>
</tr>
<tr>
<td>29</td>
<td>Caesar Vance</td>
<td>Pre-Sales Support</td>
<td>New York</td>
<td>2011/12/12</td>
<td>$106,450</td>
</tr>
<tr>
<td>56</td>
<td>Doris Wilder</td>
<td>Sales Assistant</td>
<td>Sidney</td>
<td>2010/09/20</td>
<td>$85,600</td>
</tr>
<tr>
<td>36</td>
<td>Angelica Ramos</td>
<td>Chief Executive Officer (CEO)</td>
<td>London</td>
<td>2009/10/09</td>
<td>$1,200,000</td>
</tr>
<tr>
<td>5</td>
<td>Gavin Joyce</td>
<td>Developer</td>
<td>Edinburgh</td>
<td>2010/12/22</td>
<td>$92,575</td>
</tr>
<tr>
<td>51</td>
<td>Jennifer Chang</td>
<td>Regional Director</td>
<td>Singapore</td>
<td>2010/11/14</td>
<td>$357,650</td>
</tr>
<tr>
<td>20</td>
<td>Brenden Wagner</td>
<td>Software Engineer</td>
<td>San Francisco</td>
<td>2011/06/07</td>
<td>$206,850</td>
</tr>
<tr>
<td>7</td>
<td>Fiona Green</td>
<td>Chief Operating Officer (COO)</td>
<td>San Francisco</td>
<td>2010/03/11</td>
<td>$850,000</td>
</tr>
<tr>
<td>1</td>
<td>Shou Itou</td>
<td>Regional Marketing</td>
<td>Tokyo</td>
<td>2011/08/14</td>
<td>$163,000</td>
</tr>
<tr>
<td>39</td>
<td>Michelle House</td>
<td>Integration Specialist</td>
<td>Sidney</td>
<td>2011/06/02</td>
<td>$95,400</td>
</tr>
<tr>
<td>40</td>
<td>Suki Burks</td>
<td>Developer</td>
<td>London</td>
<td>2009/10/22</td>
<td>$114,500</td>
</tr>
<tr>
<td>47</td>
<td>Prescott Bartlett</td>
<td>Technical Author</td>
<td>London</td>
<td>2011/05/07</td>
<td>$145,000</td>
</tr>
<tr>
<td>52</td>
<td>Gavin Cortez</td>
<td>Team Leader</td>
<td>San Francisco</td>
<td>2008/10/26</td>
<td>$235,500</td>
</tr>
<tr>
<td>8</td>
<td>Martena Mccray</td>
<td>Post-Sales support</td>
<td>Edinburgh</td>
<td>2011/03/09</td>
<td>$324,050</td>
</tr>
<tr>
<td>24</td>
<td>Unity Butler</td>
<td>Marketing Designer</td>
<td>San Francisco</td>
<td>2009/12/09</td>
<td>$85,675</td>
</tr>
<tr>
<td>38</td>
<td>Howard Hatfield</td>
<td>Office Manager</td>
<td>San Francisco</td>
<td>2008/12/16</td>
<td>$164,500</td>
</tr>
<tr>
<td>53</td>
<td>Hope Fuentes</td>
<td>Secretary</td>
<td>San Francisco</td>
<td>2010/02/12</td>
<td>$109,850</td>
</tr>
<tr>
<td>30</td>
<td>Vivian Harrell</td>
<td>Financial Controller</td>
<td>San Francisco</td>
<td>2009/02/14</td>
<td>$452,500</td>
</tr>
<tr>
<td>28</td>
<td>Timothy Mooney</td>
<td>Office Manager</td>
<td>London</td>
<td>2008/12/11</td>
<td>$136,200</td>
</tr>
<tr>
<td>34</td>
<td>Jackson Bradshaw</td>
<td>Director</td>
<td>New York</td>
<td>2008/09/26</td>
<td>$645,750</td>
</tr>
<tr>
<td>4</td>
<td>Olivia Liang</td>
<td>Support Engineer</td>
<td>Singapore</td>
<td>2011/02/03</td>
<td>$234,500</td>
</tr>
<tr>
<td>3</td>
<td>Bruno Nash</td>
<td>Software Engineer</td>
<td>London</td>
<td>2011/05/03</td>
<td>$163,500</td>
</tr>
<tr>
<td>31</td>
<td>Sakura Yamamoto</td>
<td>Support Engineer</td>
<td>Tokyo</td>
<td>2009/08/19</td>
<td>$139,575</td>
</tr>
<tr>
<td>11</td>
<td>Thor Walton</td>
<td>Developer</td>
<td>New York</td>
<td>2013/08/11</td>
<td>$98,540</td>
</tr>
<tr>
<td>10</td>
<td>Finn Camacho</td>
<td>Support Engineer</td>
<td>San Francisco</td>
<td>2009/07/07</td>
<td>$87,500</td>
</tr>
<tr>
<td>44</td>
<td>Serge Baldwin</td>
<td>Data Coordinator</td>
<td>Singapore</td>
<td>2012/04/09</td>
<td>$138,575</td>
</tr>
<tr>
<td>42</td>
<td>Zenaida Frank</td>
<td>Software Engineer</td>
<td>New York</td>
<td>2010/01/04</td>
<td>$125,250</td>
</tr>
<tr>
<td>27</td>
<td>Zorita Serrano</td>
<td>Software Engineer</td>
<td>San Francisco</td>
<td>2012/06/01</td>
<td>$115,000</td>
</tr>
<tr>
<td>49</td>
<td>Jennifer Acosta</td>
<td>Junior Javascript Developer</td>
<td>Edinburgh</td>
<td>2013/02/01</td>
<td>$75,650</td>
</tr>
<tr>
<td>15</td>
<td>Cara Stevens</td>
<td>Sales Assistant</td>
<td>New York</td>
<td>2011/12/06</td>
<td>$145,600</td>
</tr>
<tr>
<td>9</td>
<td>Hermione Butler</td>
<td>Regional Director</td>
<td>London</td>
<td>2011/03/21</td>
<td>$356,250</td>
</tr>
<tr>
<td>25</td>
<td>Lael Greer</td>
<td>Systems Administrator</td>
<td>London</td>
<td>2009/02/27</td>
<td>$103,500</td>
</tr>
<tr>
<td>33</td>
<td>Jonas Alexander</td>
<td>Developer</td>
<td>San Francisco</td>
<td>2010/07/14</td>
<td>$86,500</td>
</tr>
<tr>
<td>43</td>
<td>Shad Decker</td>
<td>Regional Director</td>
<td>Edinburgh</td>
<td>2008/11/13</td>
<td>$183,000</td>
</tr>
<tr>
<td>16</td>
<td>Michael Bruce</td>
<td>Javascript Developer</td>
<td>Singapore</td>
<td>2011/06/27</td>
<td>$183,000</td>
</tr>
<tr>
<td>19</td>
<td>Donna Snider</td>
<td>Customer Support</td>
<td>New York</td>
<td>2011/01/25</td>
<td>$112,000</td>
</tr>
</tbody>
</table>
Javascript (please put it below table)
var table = $('#example').DataTable({
dom : 'l<"#add">frtip'
})
$('<label/>').text('Search Column:').appendTo('#add')
$select = $('<select/>').appendTo('#add')
$('<option/>').val('All').text('All').appendTo($select);
$('<option/>').val('0').text('Seq').appendTo($select);
$('<option/>').val('1').text('Name').appendTo($select);
$('<option/>').val('2').text('Position').appendTo($select);
$('<option/>').val('3').text('Office').appendTo($select);
$('<option/>').val('4').text('Start Date').appendTo($select);
$('<option/>').val('5').text('Salary').appendTo($select);
$('input[type="search"]').on( 'keyup change', function () {
var searchValue = $(this).val();
var columnSearch = $select.val();
if(columnSearch == 'All'){
table.search(searchValue).draw();
} else {
table.columns(columnSearch).search(searchValue).draw();
}
});

Answer 1

There's a few things wrong with the code.
There isn't a listener for the change of the menu, so no redraw can occur until the user types something else in the search input box.
The val() values don't match the column indexes - so you'll be searching on the wrong columns.
The previous column searches aren't being cleared, so you'll be adding to the previous searches rather than replacing them.
All easily fixable, see the live example here, which uses the following code:
var table = $('#example').DataTable({
dom: 'l<"#add">frtip'
});
$('<label/>').text('Search Column:').appendTo('#add');
$select = $('<select/>').appendTo('#add');
$('<option/>').val('All').text('All').appendTo($select);
$('<option/>').val('0').text('Name').appendTo($select);
$('<option/>').val('1').text('Position').appendTo($select);
$('<option/>').val('2').text('Office').appendTo($select);
$('<option/>').val('3').text('Age').appendTo($select);
$('<option/>').val('4').text('Start Date').appendTo($select);
$('<option/>').val('5').text('Salary').appendTo($select);
$('input[type="search"]').on('keyup change recheck', function() {
console.log('here');
var searchValue = $(this).val();
var columnSearch = $select.val();
table.columns().every(function() {
this.search('');
});
if (columnSearch == 'All') {
table.search(searchValue).draw();
} else {
table.columns(columnSearch).search(searchValue).draw();
}
});
$select.on('change', function() {
$('input[type="search"]').trigger('recheck');
});