页面加载时的数据表条件计算

我在用 this API plugin 对于数据表,为了计算列的总和,我需要稍微修改一下。

根据文件;

DataTablesAPI的设计是完全可扩展的,使用$.fn.dataTable.api.register函数可以很容易地添加自定义函数。此函数接受两个参数:第一个参数是要添加的方法的名称及其链接层次结构,第二个参数是函数本身。

在办公室等于东京的所有行中,我如何得到年龄总和,并显示这个 外部 HTML元素中的表?我需要它在页面加载时显示,而不单击任何按钮或过滤。

下面的代码;

HTML

<p id="sum"></p> <!-- display sum of Tokyo here -->
<table id="example" class="display" style="width:100%">
        <thead>
            <tr>
                <th>Name</th>
                <th>Position</th>
                <th>Office</th>
                <th>Age</th>
                <th>Start date</th>
                <th>Salary</th>
            </tr>
        </thead>
        <tbody>
            <tr>
                <td>Tiger Nixon</td>
                <td>System Architect</td>
                <td>Edinburgh</td>
                <td>61</td>
                <td>2011/04/25</td>
                <td>$320,800</td>
            </tr>
            <tr>
                <td>Garrett Winters</td>
                <td>Accountant</td>
                <td>Tokyo</td>
                <td>63</td>
                <td>2011/07/25</td>
                <td>$170,750</td>
            </tr>
            <tr>
                <td>Ashton Cox</td>
                <td>Junior Technical Author</td>
                <td>San Francisco</td>
                <td>66</td>
                <td>2009/01/12</td>
                <td>$86,000</td>
            </tr>
            <tr>
                <td>Cedric Kelly</td>
                <td>Senior Javascript Developer</td>
                <td>Edinburgh</td>
                <td>22</td>
                <td>2012/03/29</td>
                <td>$433,060</td>
            </tr>
            <tr>
                <td>Airi Satou</td>
                <td>Accountant</td>
                <td>Tokyo</td>
                <td>33</td>
                <td>2008/11/28</td>
                <td>$162,700</td>
            </tr>
            <tr>
                <td>Brielle Williamson</td>
                <td>Integration Specialist</td>
                <td>New York</td>
                <td>61</td>
                <td>2012/12/02</td>
                <td>$372,000</td>
            </tr>
            <tr>
                <td>Herrod Chandler</td>
                <td>Sales Assistant</td>
                <td>San Francisco</td>
                <td>59</td>
                <td>2012/08/06</td>
                <td>$137,500</td>
            </tr>
            <tr>
                <td>Rhona Davidson</td>
                <td>Integration Specialist</td>
                <td>Tokyo</td>
                <td>55</td>
                <td>2010/10/14</td>
                <td>$327,900</td>
            </tr>
            <tr>
                <td>Colleen Hurst</td>
                <td>Javascript Developer</td>
                <td>San Francisco</td>
                <td>39</td>
                <td>2009/09/15</td>
                <td>$205,500</td>
            </tr>
            <tr>
                <td>Sonya Frost</td>
                <td>Software Engineer</td>
                <td>Edinburgh</td>
                <td>23</td>
                <td>2008/12/13</td>
                <td>$103,600</td>
            </tr>
            <tr>
                <td>Jena Gaines</td>
                <td>Office Manager</td>
                <td>London</td>
                <td>30</td>
                <td>2008/12/19</td>
                <td>$90,560</td>
            </tr>
            <tr>
                <td>Quinn Flynn</td>
                <td>Support Lead</td>
                <td>Edinburgh</td>
                <td>22</td>
                <td>2013/03/03</td>
                <td>$342,000</td>
            </tr>
            <tr>
                <td>Charde Marshall</td>
                <td>Regional Director</td>
                <td>San Francisco</td>
                <td>36</td>
                <td>2008/10/16</td>
                <td>$470,600</td>
            </tr>
            <tr>
                <td>Haley Kennedy</td>
                <td>Senior Marketing Designer</td>
                <td>London</td>
                <td>43</td>
                <td>2012/12/18</td>
                <td>$313,500</td>
            </tr>
            <tr>
                <td>Tatyana Fitzpatrick</td>
                <td>Regional Director</td>
                <td>London</td>
                <td>19</td>
                <td>2010/03/17</td>
                <td>$385,750</td>
            </tr>
            <tr>
                <td>Michael Silva</td>
                <td>Marketing Designer</td>
                <td>London</td>
                <td>66</td>
                <td>2012/11/27</td>
                <td>$198,500</td>
            </tr>
            <tr>
                <td>Paul Byrd</td>
                <td>Chief Financial Officer (CFO)</td>
                <td>New York</td>
                <td>64</td>
                <td>2010/06/09</td>
                <td>$725,000</td>
            </tr>
            <tr>
                <td>Gloria Little</td>
                <td>Systems Administrator</td>
                <td>New York</td>
                <td>59</td>
                <td>2009/04/10</td>
                <td>$237,500</td>
            </tr>
            <tr>
                <td>Bradley Greer</td>
                <td>Software Engineer</td>
                <td>London</td>
                <td>41</td>
                <td>2012/10/13</td>
                <td>$132,000</td>
            </tr>
            <tr>
                <td>Dai Rios</td>
                <td>Personnel Lead</td>
                <td>Edinburgh</td>
                <td>35</td>
                <td>2012/09/26</td>
                <td>$217,500</td>
            </tr>
            <tr>
                <td>Jenette Caldwell</td>
                <td>Development Lead</td>
                <td>New York</td>
                <td>30</td>
                <td>2011/09/03</td>
                <td>$345,000</td>
            </tr>
            <tr>
                <td>Yuri Berry</td>
                <td>Chief Marketing Officer (CMO)</td>
                <td>New York</td>
                <td>40</td>
                <td>2009/06/25</td>
                <td>$675,000</td>
            </tr>
            <tr>
                <td>Caesar Vance</td>
                <td>Pre-Sales Support</td>
                <td>New York</td>
                <td>21</td>
                <td>2011/12/12</td>
                <td>$106,450</td>
            </tr>
            <tr>
                <td>Doris Wilder</td>
                <td>Sales Assistant</td>
                <td>Sidney</td>
                <td>23</td>
                <td>2010/09/20</td>
                <td>$85,600</td>
            </tr>
            <tr>
                <td>Angelica Ramos</td>
                <td>Chief Executive Officer (CEO)</td>
                <td>London</td>
                <td>47</td>
                <td>2009/10/09</td>
                <td>$1,200,000</td>
            </tr>
            <tr>
                <td>Gavin Joyce</td>
                <td>Developer</td>
                <td>Edinburgh</td>
                <td>42</td>
                <td>2010/12/22</td>
                <td>$92,575</td>
            </tr>
            <tr>
                <td>Jennifer Chang</td>
                <td>Regional Director</td>
                <td>Singapore</td>
                <td>28</td>
                <td>2010/11/14</td>
                <td>$357,650</td>
            </tr>
            <tr>
                <td>Brenden Wagner</td>
                <td>Software Engineer</td>
                <td>San Francisco</td>
                <td>28</td>
                <td>2011/06/07</td>
                <td>$206,850</td>
            </tr>
            <tr>
                <td>Fiona Green</td>
                <td>Chief Operating Officer (COO)</td>
                <td>San Francisco</td>
                <td>48</td>
                <td>2010/03/11</td>
                <td>$850,000</td>
            </tr>
            <tr>
                <td>Shou Itou</td>
                <td>Regional Marketing</td>
                <td>Tokyo</td>
                <td>20</td>
                <td>2011/08/14</td>
                <td>$163,000</td>
            </tr>
            <tr>
                <td>Michelle House</td>
                <td>Integration Specialist</td>
                <td>Sidney</td>
                <td>37</td>
                <td>2011/06/02</td>
                <td>$95,400</td>
            </tr>
            <tr>
                <td>Suki Burks</td>
                <td>Developer</td>
                <td>London</td>
                <td>53</td>
                <td>2009/10/22</td>
                <td>$114,500</td>
            </tr>
            <tr>
                <td>Prescott Bartlett</td>
                <td>Technical Author</td>
                <td>London</td>
                <td>27</td>
                <td>2011/05/07</td>
                <td>$145,000</td>
            </tr>
            <tr>
                <td>Gavin Cortez</td>
                <td>Team Leader</td>
                <td>San Francisco</td>
                <td>22</td>
                <td>2008/10/26</td>
                <td>$235,500</td>
            </tr>
            <tr>
                <td>Martena Mccray</td>
                <td>Post-Sales support</td>
                <td>Edinburgh</td>
                <td>46</td>
                <td>2011/03/09</td>
                <td>$324,050</td>
            </tr>
            <tr>
                <td>Unity Butler</td>
                <td>Marketing Designer</td>
                <td>San Francisco</td>
                <td>47</td>
                <td>2009/12/09</td>
                <td>$85,675</td>
            </tr>
            <tr>
                <td>Howard Hatfield</td>
                <td>Office Manager</td>
                <td>San Francisco</td>
                <td>51</td>
                <td>2008/12/16</td>
                <td>$164,500</td>
            </tr>
            <tr>
                <td>Hope Fuentes</td>
                <td>Secretary</td>
                <td>San Francisco</td>
                <td>41</td>
                <td>2010/02/12</td>
                <td>$109,850</td>
            </tr>
            <tr>
                <td>Vivian Harrell</td>
                <td>Financial Controller</td>
                <td>San Francisco</td>
                <td>62</td>
                <td>2009/02/14</td>
                <td>$452,500</td>
            </tr>
            <tr>
                <td>Timothy Mooney</td>
                <td>Office Manager</td>
                <td>London</td>
                <td>37</td>
                <td>2008/12/11</td>
                <td>$136,200</td>
            </tr>
            <tr>
                <td>Jackson Bradshaw</td>
                <td>Director</td>
                <td>New York</td>
                <td>65</td>
                <td>2008/09/26</td>
                <td>$645,750</td>
            </tr>
            <tr>
                <td>Olivia Liang</td>
                <td>Support Engineer</td>
                <td>Singapore</td>
                <td>64</td>
                <td>2011/02/03</td>
                <td>$234,500</td>
            </tr>
            <tr>
                <td>Bruno Nash</td>
                <td>Software Engineer</td>
                <td>London</td>
                <td>38</td>
                <td>2011/05/03</td>
                <td>$163,500</td>
            </tr>
            <tr>
                <td>Sakura Yamamoto</td>
                <td>Support Engineer</td>
                <td>Tokyo</td>
                <td>37</td>
                <td>2009/08/19</td>
                <td>$139,575</td>
            </tr>
            <tr>
                <td>Thor Walton</td>
                <td>Developer</td>
                <td>New York</td>
                <td>61</td>
                <td>2013/08/11</td>
                <td>$98,540</td>
            </tr>
            <tr>
                <td>Finn Camacho</td>
                <td>Support Engineer</td>
                <td>San Francisco</td>
                <td>47</td>
                <td>2009/07/07</td>
                <td>$87,500</td>
            </tr>
            <tr>
                <td>Serge Baldwin</td>
                <td>Data Coordinator</td>
                <td>Singapore</td>
                <td>64</td>
                <td>2012/04/09</td>
                <td>$138,575</td>
            </tr>
            <tr>
                <td>Zenaida Frank</td>
                <td>Software Engineer</td>
                <td>New York</td>
                <td>63</td>
                <td>2010/01/04</td>
                <td>$125,250</td>
            </tr>
            <tr>
                <td>Zorita Serrano</td>
                <td>Software Engineer</td>
                <td>San Francisco</td>
                <td>56</td>
                <td>2012/06/01</td>
                <td>$115,000</td>
            </tr>
            <tr>
                <td>Jennifer Acosta</td>
                <td>Junior Javascript Developer</td>
                <td>Edinburgh</td>
                <td>43</td>
                <td>2013/02/01</td>
                <td>$75,650</td>
            </tr>
            <tr>
                <td>Cara Stevens</td>
                <td>Sales Assistant</td>
                <td>New York</td>
                <td>46</td>
                <td>2011/12/06</td>
                <td>$145,600</td>
            </tr>
            <tr>
                <td>Hermione Butler</td>
                <td>Regional Director</td>
                <td>London</td>
                <td>47</td>
                <td>2011/03/21</td>
                <td>$356,250</td>
            </tr>
            <tr>
                <td>Lael Greer</td>
                <td>Systems Administrator</td>
                <td>London</td>
                <td>21</td>
                <td>2009/02/27</td>
                <td>$103,500</td>
            </tr>
            <tr>
                <td>Jonas Alexander</td>
                <td>Developer</td>
                <td>San Francisco</td>
                <td>30</td>
                <td>2010/07/14</td>
                <td>$86,500</td>
            </tr>
            <tr>
                <td>Shad Decker</td>
                <td>Regional Director</td>
                <td>Edinburgh</td>
                <td>51</td>
                <td>2008/11/13</td>
                <td>$183,000</td>
            </tr>
            <tr>
                <td>Michael Bruce</td>
                <td>Javascript Developer</td>
                <td>Singapore</td>
                <td>29</td>
                <td>2011/06/27</td>
                <td>$183,000</td>
            </tr>
            <tr>
                <td>Donna Snider</td>
                <td>Customer Support</td>
                <td>New York</td>
                <td>27</td>
                <td>2011/01/25</td>
                <td>$112,000</td>
            </tr>
        </tbody>
        <tfoot>
            <tr>
                <th>Name</th>
                <th>Position</th>
                <th>Office</th>
                <th>Age</th>
                <th>Start date</th>
                <th>Salary</th>
            </tr>
        </tfoot>
    </table>

JS

$.fn.dataTable.Api.register( 'column().data().sum()', function () {
    return this.reduce( function (a, b) {
        var x = parseFloat( a ) || 0;
        var y = parseFloat( b ) || 0;
        return x + y;
    } );
} );

/* Init the table and fire off a call to get the hidden nodes. */
$(document).ready(function() {
    var table = $('#example').DataTable();

    $('<button>Click to sum age in all rows</button>')
        .prependTo( '#demo' )
        .on( 'click', function () {
            alert( 'Column sum is: '+ table.column( 3 ).data().sum() );
        } );

    $('<button>Click to sum age of visible rows</button>')
        .prependTo( '#demo' )
        .on( 'click', function () {
            alert( 'Column sum is: '+ table.column( 3, {page:'current'} ).data().sum() );
        } );
} );