I have a drop-down fields that when changed should display a button that can download files based on drop-down selection. The problem is it keeps appending button, so if 1 is selected, it shows 1 button, on selecting another option, it appends another button and so on. So, with every selection, button keeps adding up instead of just showing one 1 button. I tried adding $('#buttondownload').remove(), but its not working properly. Here is the code:

```js
     function showFields(this) {
     if (this.value == "1" || this.value == "2")
   {
  download.style.display = "block";
   }
   if (this.value == "")
   {
  download.style.display = "none";
   }
   if (this.value == "1")
   {
  var file = "'test.pdf";
   }
  if (this.value == "2")
  {
  var file = "test2.pdf";
  }
     html = '<button type="button" onClick="location.href='+ file + '">Download File</button>'
 $('#buttonDownload').append(html);
}
```

```html
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<select id="ID" name="ID" onChange="showFields(this);">
  <option value="">Select</option>
  <option value="1">1</option>
        <option value="2">2</option>
  </select>
     <div id="download"><div id="buttonDownload"></div></div>
```