可以计算出有多少数据被加载使用AJAX？ [英] Possible to calculate how much data been loaded with AJAX?

问题描述

我一直忙于一些AJAX code。我想计算有多少数据被加载，我想用百分比显示。

I've been busy with some AJAX code. I want to calculate how much data has been loaded and I want to display it with percents.

我所有的preloaded信息是里面的反馈。 我可以计算出有多少数据包含（以字节为单位），并且我也看到了进步？就像当它装：10KB，20KB，30KB等

All my preloaded info is inside "feedback". Can I calculate how much DATA it contains (in bytes) and can I also view the progress? Like when it has loaded: 10kb, 20kb, 30kb etc

我的code：

function calc(page)
    {
    $('#pageLoad h2').animate({ marginTop : '0px'}, 200);
        $.ajax(
        {
            url:            './pages/page.php',
            type:           'POST',
            data:           'page='+page,
            success:        function( feedback )
            {
                $('#content').html( feedback );
            }                               

        });
    };

对不起，我的英文不好。

Sorry for my poor english.

推荐答案

它的是的可能。 XHRs有 进度事件。唯一的问题是访问XHR对象 - 不幸的是 beforeSend 只接收 jqXHR 对象，而不是底层的XHR对象。它也不是作为包装物的属性进行访问。您可以通过添加下列选项， $但挂钩到XHR对象的创建过程阿贾克斯（）：

It is possible. XHRs have a progress event. The only problem is accessing the XHR object - unfortunately beforeSend only receives the jqXHR object and not the underlying XHR object. It is also not accessible as a property of the wrapper. You can however hook into the creation process of the XHR object by adding the following option to $.ajax():

xhr: function () {
    var xhr = $.ajaxSettings.xhr(); // call the original function
    xhr.addEventListener('progress', function (e) {
        if (e.lengthComputable) {
            var percentComplete = e.loaded / e.total;
            // Do something with download progress
        }
    }, false);
    return xhr;
}

---

下面是我最初的解决方案。这是非常难以与jQuery结合起来，因为你不能轻易地勾到onreadystatechange的处理程序，并不能安全地更换它已设置之后：

---

Here's my initial solution. It is extremely hard to combine with jQuery since you can't easily hook into the onreadystatechange handler and cannot safely replace it after it has been set:

<打击>您需要添加一个自定义的的onreadystatechange 处理程序。当的readyState 的XHR对象变成 2 （* HEADERS_RECEIVED *），您可以访问内容长度头得到的总大小，然后等待事件触发与 xhr.readyState == 3 （加载）。

You need to add a custom onreadystatechange handler. When the readyState of the XHR object becomes 2 (*HEADERS_RECEIVED*) you can access the Content-Length header to get the total size and then wait for the event to fire with xhr.readyState == 3 (LOADING).

然后你可以通过查看 xhr.responseText.length 计算的进展。
然而，这将仅一次。所以，你需要启动一个定时器（使用的setInterval（）），这将检查准备状态和反应的大小如每100毫秒。一旦请求完成，然后再次使用停止时间间隔 clearInterval（）。

Then you can calculate the progress by looking at xhr.responseText.length.
However, this will only fire once. So you need to start a timer (using setInterval()) which will check the ready state and response size e.g. every 100 msecs. As soon as the request finishes you stop the interval again using clearInterval().

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