关于 js 下载PDF文件时 无法直接下载 要先预览

import FileSave from ‘file-saver‘;


downloadPDF(URLToPDF,PDFName) {
      var oReq = new XMLHttpRequest();
      oReq.open("GET", URLToPDF, true);
      oReq.responseType = "blob";
      oReq.onload = function() {
        var file = new Blob([oReq.response], { 
            type: ‘application/pdf‘ 
        });
        FileSave.saveAs(file, PDFName);
      };
      oReq.send();
 },