XmlHttpRequest onprogress 间隔

问题描述

我正在使用 XmlHttpRequests 将图像上传到服务器，我想向用户显示这些上传的进度.

I'm using XmlHttpRequests to upload images to a server and I'd like to show the user the progress of these uploads.

不幸的是，对我的 onprogress-event 处理程序的调用之间的间隔太大.对于 500k 的图像，通常只调用一次或两次 onprogress.

Unfortunately the interval between calls to my onprogress-event handler is too large. Usually onprogress is called only once or twice for a 500k image.

这是我的代码:

/* This function is not called often enough */
function progress(e){
    console.log('Uploading: ' + Math.round((e.loaded / e.total) * 100) + ' %');
}

var xhr = new XMLHttpRequest();
xhr.upload.addEventListener('progress', progress, false);
xhr.send(data);

是否可以更改此行为，或者是否可以在浏览器实现中的某处对其进行硬编码?

Can this behaviour be changed or is this hardcoded somewhere in the browser implementation?

推荐答案

W3 在他们的 XMLHttpRequest 级别 2 文档.显然，跨浏览器的不同级别的一致性是可以预料的.

The W3 sets forth the following guidelines in their XMLHttpRequest Level 2 document. Obviously varying levels of conformance across browsers are to be expected.

上传:

当请求实体正文被上传并且上传完成标志为假时，排队一个任务以在 XMLHttpRequestUpload 对象上触发一个名为 progress 的进度事件，大约每 50 毫秒或传输的每个字节，以最不频繁的为准.- W3 XMLHttpRequest Level 2(粗体表示强调)