title: How to click save as button when downloading a file?
body: <p>When clicking on a link for example:</p>
  
  <pre><code>&lt;a href="1.txt"&gt;Download&lt;/a&gt;
  </code></pre>
  
  <p>a save as window will pop up. Is it possible to use JavaScript to click buttons on the window? Or, can a call back function be set when the button is clicked?</p>