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
});