axios

            downloadFile(fileId) {
            axios({
                url: 'http://localhost:8081/download?fileId=' + fileId,
                method: 'GET',
                responseType: 'blob',
                headers: {
                    Authorization: 'Basic ' + localStorage.getItem('user')
                }}).then((response) => {
                const url = window.URL.createObjectURL(new Blob([response.data]));
                const link = document.createElement('a');
                link.href = url;
                link.setAttribute('download', 'file.pdf'); //or any other extension
                document.body.appendChild(link);
                link.click();
                });
            }