title: POST immediately after select a file
body: <p>I have the following HTML code</p>
  
  <pre><code>&lt;form action="/script/upload_key.py" method="POST" enctype="multipart/form-data"&gt; 
      Key filename: &lt;input name="file_1" type="file"&gt; 
      &lt;input name="submit" type="submit"&gt; 
  &lt;/form&gt; 
  </code></pre>
  
  <p>which gives me the following stuff.</p>
  
  <p><img src="https://i.stack.imgur.com/xkHea.png" alt="alt text"></p>
  
  <p>I was wondering</p>
  
  <ol>
  <li>How I can use JavaScript, to eliminate the need of <code>Submit</code> button. That's mean, once I <code>Choose File</code>, the selected file will be uploaded immediately?</li>
  <li>How can I make sure the field to display selected file name is long enough, so that ... will not be shown?</li>
  </ol>