web下载附件及修改名称

 /**
  * @param: url 附件地址
  * @param: filename 下载后的文件名
  */
 function download(url, filename) {
     getBlob(url, function (blob) {
         saveAs(blob, filename);
     });

 }

 function getBlob(url, cb) {

     var xhr = new XMLHttpRequest();

     xhr.open('GET', url, true);

     xhr.responseType = 'blob';

     xhr.onload = function () {

         if (xhr.status === 200) {

             cb(xhr.response);

         }

     };

     xhr.send();

 }

 function saveAs(blob, filename) {

     if (window.navigator.msSaveOrOpenBlob) {

         navigator.msSaveBlob(blob, filename);

     } else {

         var link = document.createElement('a');

         var body = document.querySelector('body');

         link.href = window.URL.createObjectURL(blob);

         link.download = filename;

         // fix Firefox

         link.style.display = 'none';

         body.appendChild(link);

         link.click();

         body.removeChild(link);

         window.URL.revokeObjectURL(link.href);

     };

 }