file upload using hidden iframe

file upload using hidden iframe

below is the code of file upload using hidden i frame which i copied from
a website, but i don't know where did the ifame called "comment.php"
<script language="Javascript">
function fileUpload(form, action_url, div_id) {
// Create the iframe...
var iframe = document.createElement("iframe");
iframe.setAttribute("id", "upload_iframe");
iframe.setAttribute("name", "upload_iframe");
iframe.setAttribute("width", "0");
iframe.setAttribute("height", "0");
iframe.setAttribute("border", "0");
iframe.setAttribute("style", "width: 0; height: 0; border: none;");
// Add to document...
form.parentNode.appendChild(iframe);
window.frames['upload_iframe'].name = "upload_iframe";
var iframeId = document.getElementById("upload_iframe");
// Add event...
var eventHandler = function () {
if (iframeId.detachEvent) iframeId.detachEvent("onload",
eventHandler);
else iframeId.removeEventListener("load", eventHandler, false);
// Message from server...
if (iframeId.contentDocument) {
content = iframeId.contentDocument.body.innerHTML;
} else if (iframeId.contentWindow) {
content = iframeId.contentWindow.document.body.innerHTML;
} else if (iframeId.document) {
content = iframeId.document.body.innerHTML;
}
document.getElementById(div_id).innerHTML = content;
// Del the iframe...
setTimeout('iframeId.parentNode.removeChild(iframeId)', 500);
}
if (iframeId.addEventListener) iframeId.addEventListener("load",
eventHandler, true);
if (iframeId.attachEvent) iframeId.attachEvent("onload", eventHandler);
// Set properties of form...
form.setAttribute("target", "upload_iframe");
form.setAttribute("action", action_url);
form.setAttribute("method", "post");
form.setAttribute("enctype", "multipart/form-data");
form.setAttribute("encoding", "multipart/form-data");
// Submit the form...
form.submit();
document.getElementById(div_id).innerHTML = "Uploading...";
}
</script>
<!-- index.php could be any script server-side for receive uploads. -->
<form>
enter style-:
<input type="text" name="styles" />
enter pic:-
<input type="file" name="datafile" /></br>
<input type="button" value="upload"
onClick="fileUpload(this.form,'comment.php','upload'); return false;" >
<div id="upload"></div>
</form>