前端下载文件，base64数据转blob格式下载

遇到下载需求，后端把文件转成了base64数据返到前端，下面描述下拿到这个base64数据转成blob格式在前端下载的方法：

 

downloadAttachment({ attachmentId: id })
    .then(({ data }) => {
      proxy.$modal.closeLoading();
      const raw = window.atob(data.content);
      const rawLength = raw.length;
      const uInt8Array = new Uint8Array(rawLength);
      for (let i = 0; i < rawLength; ++i) {
        uInt8Array[i] = raw.charCodeAt(i);
      }
      const blob = new Blob([uInt8Array], { type: data.contentType });
      const elink = document.createElement("a");
      elink.download = data.attachName;
      elink.style.display = "none";
      elink.href = URL.createObjectURL(blob);
      document.body.appendChild(elink);
      elink.click();
    })
    .catch(() => {
      proxy.$modal.closeLoading();
    });