使用HTML和JavaScript通过AJAX将文件上传到IIS服务器

<form id="uploadForm" enctype="multipart/form-data">
  <input type="file" id="fileInput" name="file">
  <input type="button" value="上传" onclick="uploadFile()">
</form>

function uploadFile() {
  var fileInput = document.getElementById("fileInput");
  var file = fileInput.files[0];
  
  var formData = new FormData();
  formData.append("file", file);
  
  var xhr = new XMLHttpRequest();
  xhr.open("POST", "/upload", true);
  
  xhr.onreadystatechange = function() {
    if (xhr.readyState === 4 && xhr.status === 200) {
      // 上传成功
      console.log(xhr.responseText);
    }
  };
  
  xhr.send(formData);
}

[HttpPost]
public ActionResult Upload(HttpPostedFileBase file)
{
  if (file != null && file.ContentLength > 0)
  {
    var fileName = Path.GetFileName(file.FileName);
    var path = Path.Combine(Server.MapPath("~/uploads"), fileName);
    file.SaveAs(path);
    return Content("文件上传成功");
  }
  
  return Content("文件上传失败");
}