title: show gif loader when image is uploading
body: <p>I have a form where I am uploading files (images) through browse button.
  I want to show a loader when a user clicks on upload button once he browse any image from his/her system.</p>
  
  <p>I have no clue how can I make it work.
  Here is my code.</p>
  
  <pre><code>&lt;div style="font-family: Verdana, Geneva, sans-serif; font-size: 12px; line-height: 1.5em;"&gt;
          &lt;div&gt;
              &lt;p&gt;
                  &lt;label for="flUpload" id="lblInstructions"&gt;&lt;span class="QLabel" id="lblInstruction"&gt;Click the first button below to find your file. After selecting the file, click &lt;b&gt;Upload&lt;/b&gt;.&lt;/span&gt;&lt;/label&gt;&lt;/p&gt;
              &lt;input type="file" id="flUpload" name="flUpload"&gt;
              &lt;input type="hidden" id="hdnFileStub" name="hdnFileStub"&gt;
              &lt;input type="hidden" id="HdnFileName" name="HdnFileName"&gt;
              &lt;input type="hidden" value="4e7263a4-472b-4ad8-9e9e-79612053a13a" id="hdnQuestionStub" name="hdnQuestionStub"&gt;
              &lt;p&gt;&lt;span style="padding: 2 0; color: Red" id="ErrMessage"&gt;&lt;/span&gt;&lt;/p&gt;
          &lt;/div&gt;
          &lt;div style="margin-top: 15px; text-align: center"&gt;
              &lt;input type="submit" class="srFormButton" id="btnUpload" value="Upload" name="btnUpload"&gt;
          &lt;/div&gt;
      &lt;/div&gt;
  </code></pre>
  
  <p>Thanks,</p>