a标签下载

function downloadFile(url){
  let a= document.createElement('a');
  a.href = file.url;
  a.download = file.name;  //文件名
  a.target="_blank";
  a.click();
}

a标签download属性只在同域下有效

bolb对象实现

downloadFile(fileUrl,fileName){
      const xhr = new XMLHttpRequest();
      xhr.open('GET',fileUrl,true);
        xhr.responseType="bolb";
        xhr.onload = function (){
        if(xhr.status===200){
           var a = document.createElement('a');
            a.href = window.URL.createObjectURL(xhr.response);
            a.download = fileName;//文件名
            a.click();    
          }
        }
        xhr.send();
    }