download function do not work

const saveFolder = () => {
FileSaver.saveAs(
'serverurl/proj/otbstorage/logs/sched-432cc428-ddae-11ed-bad5-662cc6ee3b0c/mb_output_ids.txt',
'a.txt',
);
};

Above is my code, instead of download the file, the browser directly open the file.
I google a lot recently, it may caused by fetching file from serverurl not localhost.
But i can not find any way to fix this.
Can anyone take a look and help about this issue?