前端文件下载

function download(url, filename) {
    return fetch(url).then(res => res.blob().then(blob => {
        let a = document.createElement('a');
        let url = window.URL.createObjectURL(blob);
        a.href = url;
        a.download = filename;
        a.click();
        window.URL.revokeObjectURL(url);
    }))
}