JS倒計時幾秒按鈕關閉

HTML:
<button id="closeButton"  class="btn btn-success" style="size: 26px;width: 240px;height: 40px" οnclick="closetself()">關閉</button>

 JS:

function  closetself() {
    window.external.close();
}
//倒計時
var time = 5;
var timeSet;
function loadingclose(){
    time=time-1;
    var closeButton = $("#closeButton");
    if(time == 0){
        window.external.close();
    }else{
        closeButton.text("執行完畢("+time+")秒後自動關閉");
        timeSet = setTimeout(function() {
            loadingclose();
        },1000)
    }
}