本方法适用于下载到本地的文件的xlsx.js

1. 找到xlsx.core.min.js文件

2. 搜索write_ws_xml_pagesetup方法

3. 找到下面这行

   write_ws_xml_pagesetup(setup){var pageSetup=writextag("pageSetup",null,{scale:setup.scale||"100",orientation:setup.orientation||"portrait",horizontalDpi:setup.horizontalDpi||"4294967292",verticalDpi:setup.verticalDpi||"4294967292"});

4. 在write_ws_xml_pagesetup方法中添加paperSize: setup.pagesize || "9",

5. 结果为：

   write_ws_xml_pagesetup(setup){var pageSetup=writextag("pageSetup",null,{paperSize: setup.pagesize || "9",scale:setup.scale||"100",orientation:setup.orientation||"portrait",horizontalDpi:setup.horizontalDpi||"4294967292",verticalDpi:setup.verticalDpi||"4294967292"});

6. 结构参考

   function write_ws_xml_pagesetup(setup) {
       var pageSetup = writextag("pageSetup", null, {
           paperSize: setup.pagesize || "9", //重点是这个参数
           scale: setup.scale || "100",
           orientation: setup.orientation || "portrait",
           horizontalDpi: setup.horizontalDpi || "4294967293",
           verticalDpi: setup.verticalDpi || "4294967293"
       });
       return pageSetup
   }

参考：基于XLSX-STYLE通过纯前端的方式导出Excel，并且能够设置打印的边距和纸张大小