用js生成下载文件

function downloadFile(fileName, content) {
    var aLink = document.createElement('a');
    var blob = new Blob([content]);
    var evt = document.createEvent("HTMLEvents");
    evt.initEvent("click", false, false);
    aLink.download = fileName;
    aLink.href = URL.createObjectURL(blob);
    aLink.dispatchEvent(evt);
}