JS 实现图片下载

• 使用下列fetch方法传入图片地址，可触发图片下载

	  fetch(url).then((res) =>
        res.blob().then((blob) => {
          var a = document.createElement("a");
          var url = window.URL.createObjectURL(blob);
          var filename = name || "pic.jpg";
          a.href = url;
          a.download = filename;
          a.click();
          window.URL.revokeObjectURL(url);
        })
      );