arkadaşlar şöyle bir form hazırladım. upload kısmını bir scriptten aldım da burada ben upload edilen dosyanın uzantısını nasıl öğrenebilirim acaba?

<div id="uploadform">
  <script>
function send() {
javascript: location = 'upload.asp?hqtp=sent';	
}
</script>

			<h3><span>SEND YOUR PHOTO</span></h3>
			<fieldset><legend>Send Your Photo</legend>
			<p class="first">
					<input placeholder="Write Your Name" type="text" name="name" id="name" size="30" />
				</p>
				<p>
					<input placeholder="Write Your Email" type="text" name="email" id="email" size="30" />
				</p>
                <p>
					<input placeholder="Write Photo's Country" type="text" name="country" id="country" size="30" />
			</p>	
				<p>
				  <input placeholder="Write Photo's City" type="text" name="city" id="city" size="30" />
				</p>
                <p>
				  <button id="choosebutton" onClick="document.querySelector('input#button22').click()">CHOOSE A PHOTO</button>
<input id="button22" style="visibility: collapse; width: 0px;" type="file" onChange="upload(this.files[0])">
                  </p>
<script>
 
    window.ondragover = function(e) {e.preventDefault()}
    window.ondrop = function(e) {e.preventDefault(); upload(e.dataTransfer.files[0]); }
    function upload(file) {
 
        if (!file || !file.type.match(/image.*/)) return;
 
        document.body.className = "uploading";
 
        /* Lets build a FormData object*/
        var fd = new FormData(); // I wrote about it: https://hacks.mozilla.org/2011/01/how-to-develop-a-html5-image-uploader/
        fd.append("image", file); // Append the file
        fd.append("key", "6528448c258cff474ca9701c5bab6927"); // Get your own key http://api.imgur.com/
        var xhr = new XMLHttpRequest(); // Create the XHR (Cross-Domain XHR FTW!!!) Thank you sooooo much imgur.com
        xhr.open("POST", "http://api.imgur.com/2/upload.json"); // Boooom!
        xhr.onload = function() {
            // Big win!
            document.querySelector("#link").value = JSON.parse(xhr.responseText).upload.links.imgur_page;
            document.body.className = "uploaded";
        }
       
        xhr.send(fd);
    }
</script>
<style>
    #link, #uploadingbarr , #uploadbutton1 {display: none}
    #uploadbutton1 {display: inline-block;}
    .uploading #uploadingbarr {display: inline}
    .uploaded #link {display: inline}
</style>
<p id="uploadingbarr"><img src="images/uploading.gif" /></p>
<input name="resimurl" readonly="readonly" type="text" id="link" size="35" >
				<p class="submit"><button id="sendbutton" onClick="send();" type="submit">Send Your Photo</button></p>					
			</fieldset>									
 </div>