How to use the percollate.pdf function in percollate

percollate.configure();
      percollate.pdf(arr[i - 1], {
        output: (i - 1) + name,
        css,
        usePup
      });
      if (i === arr.length) {
        i = 0
        // 获得未生成pdf文件的index值
        unsavedFiles = utils.getUnsavedIndex(arr.length)
        return
      }
      // 第一次生成失败的再次生成
      if (unsavedFiles.length) {
        percollate.configure();
        percollate.pdf(arr[unsavedFiles[i - 1]], {
          output: (unsavedFiles[i - 1]) + name,
          css,
          usePup
        });
      } else {
        utils.mergePdfs(arr.length, '廖雪峰JavaScript全栈教程.pdf')
        task.cancel()
      }
    });

getHtml(pageApi).then(res => {
    const urlList = getUrlList(res, wrapEle, url);
    percollate.configure();
    percollate.pdf(urlList, {
      output: name,
      css,
      usePup
    });
  });
}