ajax无刷新上传

<input type="file" id="file" multiple="true"/>
<button onclick="upload()">upload</button>
<script>
function upload(){
var file = document.getElementById("file").files;
var formData = new FormData();
formData.append("file",file[0]);
var ajax = new XMLHttpRequest();
ajax.onreadystatechange=function()
{
if(ajax.status==200 && ajax.readyState==4){
console.log(ajax.responseText);
}
}
ajax.open("post","xhr.php");
ajax.send(formData);
}
</script>

<?php
$name=$_FILES['file']['name'];
move_uploaded_file($_FILES['file']['tmp_name'],iconv("UTF-8","gb2312",$name))