jQuery: FormData() doesn't work
<p>I made a really really simple example to test whether <code>jQuery</code>'s <code>FormData</code> work or not.</p>

<p><strong>html</strong></p>

<pre><code>&lt;form id="frm" action="/fileupload" method="post"&gt;
&lt;input type="file" name="uploadfile" /&gt;
&lt;input type="file" name="uploadfile" /&gt;
&lt;input type="button" id="uploadbutton" value="클릭" /&gt;
&lt;/form&gt;
</code></pre>

<p>And I import <code>jQuery</code> cdn:</p>

<pre><code>&lt;script src="https://code.jquery.com/jquery-2.2.3.min.js"&gt;&lt;/script&gt;
</code></pre>

<p>I select some image file from my computer.</p>

<p>And execute folloing code in <code>Chrome development tool</code> :         </p>

<pre><code>&gt;&gt; var form = $('#frm');
&gt;&gt; form

&lt;form id="frm" action="/fileupload" method="post"&gt;
&lt;input type="file" name="uploadfile" /&gt;
&lt;input type="file" name="uploadfile" /&gt;
&lt;input type="button" id="uploadbutton" value="클릭" /&gt;
&lt;/form&gt;


&gt;&gt; var formData = new FormData(form);
&gt;&gt; formData
</code></pre>

<p>And it shows just,</p>

<pre><code>FormData {}
</code></pre>

<p>It doesn't contain any values. It was empty . Why does it not work?</p>