Question

我已经完成了一些代码，可以将多个文件从浏览器上传到服务器，同时也显示了进度条。 XHR2发送调用是异步的。问题是我希望在所有XHR2发送调用完成后调用一些函数。

以下是我的代码的一个非常简化的片段：

<input id="upload" multiple="multiple" />

<script>
var files = document.getElementById("upload").files;
for (var i = 0, length = files.length; i < length; i++) {
   var file = files[i];
   var uploadFunc = function (arg) {
      return function () {
         processXHR(arg);
      };
   }(file);      
   uploadFunc();
}

function processXHR(file) {
   var normalizedFileName = getNormalizedName(file.name);
   var url = 'upload_file/';
   var formData = new FormData();
   formData.append("docfile", file);
   var xhr = new XMLHttpRequest();
   var eventSource = xhr.upload;
   eventSource.addEventListener("progress", function (evt) {
      var position = evt.position || evt.loaded;
      var total = evt.totalSize || evt.total;
      console.log('progress_' + normalizedFileName);
      console.log(total + ":" + position);
      $('#progress_' + normalizedFileName).css('width', (position * 100 / total).toString() + '%');
   }, false);
   eventSource.addEventListener("loadstart", function (evt) {
      console.log('loadstart');
   }, false);
   eventSource.addEventListener("abort", function (evt) {
      console.log('abort');
   }, false);
   eventSource.addEventListener("error", function (evt) {
      console.log('error');
   }, false);
   eventSource.addEventListener("timeout", function (evt) {
      console.log('timeout');
   }, false);
   xhr.onreadystatechange = function (evt) {
      if (xhr.readyState == 4) {
         console.log('onreadystatechange: File uploaded.');
      }
   };
    xhr.open('post', url, true);
    xhr.send(formData);
}
</script>

每当“onreadystatechange：File upload”。在控制台打印，我知道其中一个文件已完成上传。但我无法编写任何会说“所有文件已上传。”的代码。

感谢您的帮助。 我正在使用jquery，以防某些人使用jquery有解决方案。

Answer 1

你知道你打了几个电话吗？如果是这样，至少ajax回调，你检查计数。像

这样的东西

if (ajaxCallCount === ajaxCallsLength) {
 // Do stuff involving post all ajax calls
} else {
 ajaxCallCount++;
}

Answer 2

在你的情况下你需要一个计数器和setInterval方法，试试这个：

<input id="upload" multiple="multiple" />

<script>
var files = document.getElementById("upload").files;
var counter = 0;

for (var i = 0, length = files.length; i < length; i++) {
   var file = files[i];
   var uploadFunc = function (arg) {
      return function () {
         processXHR(arg);
      };
   }(file);      
   uploadFunc();
}

var interval = setInterval(function() {
    if(counter == files.length) {
        clearInterval(interval);
        console.log("All Files uploaded!");
    }
}, 100);

function processXHR(file) {
   var normalizedFileName = getNormalizedName(file.name);
   var url = 'upload_file/';
   var formData = new FormData();
   formData.append("docfile", file);
   var xhr = new XMLHttpRequest();
   var eventSource = xhr.upload;
   eventSource.addEventListener("progress", function (evt) {
      var position = evt.position || evt.loaded;
      var total = evt.totalSize || evt.total;
      console.log('progress_' + normalizedFileName);
      console.log(total + ":" + position);
      $('#progress_' + normalizedFileName).css('width', (position * 100 / total).toString() + '%');
   }, false);
   eventSource.addEventListener("loadstart", function (evt) {
      console.log('loadstart');
   }, false);
   eventSource.addEventListener("abort", function (evt) {
      console.log('abort');
   }, false);
   eventSource.addEventListener("error", function (evt) {
      console.log('error');
   }, false);
   eventSource.addEventListener("timeout", function (evt) {
      console.log('timeout');
   }, false);
   xhr.onreadystatechange = function (evt) {
      if (xhr.readyState == 4) {
         counter += 1;
      }
   };
    xhr.open('post', url, true);
    xhr.send(formData);
}
</script>

如何等待所有XHR2发送呼叫完成

2 个答案: