【发布时间】：2019-03-28 16:34:00
【问题描述】：
我使用this API plugin的数据表来计算一列的总和，我需要稍微修改一下。
根据文档；
DataTables API 被设计成完全可扩展的，使用 $.fn.dataTable.Api.register 函数可以很容易地添加自定义函数。这个函数有两个参数；第一个是要添加的方法的名称及其链接层次结构，第二个是函数本身。
如何获得 office 等于 Tokyo 的所有行中的年龄总和，并在 html 元素中显示该表的 outside？我需要它在页面加载时显示，无需点击任何按钮或过滤。
代码如下；
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() );
} );
} );
【问题讨论】：
标签： javascript jquery datatable datatables