Error getting table with the property 'document.getElementById' in AngularJS

I am trying to get a table generated in html with the aforementioned property, for the generation of an .xls file If I pass the direct value, my .xls is perfectly accommodated as I require it:

        vmHome.table = "<table><tr><th>Saldo en Coppel</th><th>Cuentas activas coppel</th><th>Saldo por cuenta</th></tr><tr> <td rowspan='3'>$17,000.00</td><td>Ropa</td><td>$10,000.00</td></tr><tr> <td>Muebles</td><td>$2,000.00</td></tr><tr> <td>Prestamos</td><td>$5,000.00</td></tr><tr> <td rowspan='2'>$23,000.00</td><td>Ropa</td><td>$15,000.00</td></tr><tr> <td>Muebles</td><td>$8,000.00</td></tr></table>"

The error happens when you get the table with the following line of code:

HTML:

<button type="button"  class="btn btn-default" ng-click="vmHome.generateExcel()">Export</button>
 <table id="tablaDatos">
<tr>
    <th>Saldo en Coppel</th>
    <th>Cuentas activas coppel</th>
    <th>Saldo por cuenta</th>
</tr>
<tr> 
    <td rowspan='3'>$17,000.00</td>
    <td>Ropa</td>
    <td>$10,000.00</td>
</tr>
<tr> 
    <td>Muebles</td>
    <td>$2,000.00</td>
</tr>
<tr> 
    <td>Prestamos</td>
    <td>$5,000.00</td>
</tr>
<tr> 
    <td rowspan='2'>$23,000.00</td>
    <td>Ropa</td>
    <td>$15,000.00</td>
</tr>
<tr> 
    <td>Muebles</td>
    <td>$8,000.00</td>
    </tr></table>

CONTROLLER:

        vmHome.generateExcel = function() {
          var tablahtml = document.getElementById('tablaDatos').innerHTML;
          vmHome.downloadCSV(tablahtml,'reporte.xls');

       }

And it's what I need for export, my .xls is not generated correctly.