1. 监听请求成功: xhr.onload
2. 监听请求失败: xhr.onerror
3. 监听请求数据下载中: xhr.onprogress
xhr.onload = function() { var responseText = xhr.responseText; console.log(responseText); // process the response. }; xhr.onabort = function () { console.log('The request was aborted'); }; xhr.onprogress = function (event) { console.log(event.loaded); console.log(event.total); }; xhr.onerror = function() { console.log('There was an error!'); };
注意: xhr.onprogress是其中仅有的一个具有事件参数的事件监听属性, e.loaded表示下载了多少数据, e.total表示数据总量, e.lengthComputable 表示加载进度是否可计算.
