HTML5 FormData & jQuery上传文件

var fd = new FormData(document.getElementById("fileinfo"));
fd.append("CustomField","This is some extra data");
$.ajax({
  url: "stash.PHP",type: "POST",data: fd,processData: false,// 告诉jQuery不要去处理发送的数据
  contentType: false   // 告诉jQuery不要去设置Content-Type请求头
});