html：

<button class="download" onclick=" download('url')">
              <i class="layui-icon layui-icon-download-circle"></i>
 </button>

url為要下載原始檔的地址。

Javascript

function download(src) {
    var $a = document.createElement('a');
    $a.setAttribute("href", src);
    $a.setAttribute("download", "");
    var evObj = document.createEvent('MouseEvents');
    evObj.initMouseEvent( 'click', true, true, window, 0, 0, 0, 0, 0, false, false, true, false, 0, null);
    $a.dispatchEvent(evObj);
}