function show() {
var obj = document.getElementById(andon_obj);
if (obj.style.visibility == "visible")
obj.style.visibility = "hidden";
else
obj.style.visibility = "visible";
}
var timer=setInterval(show(), 600);
show()無返回值,setInterval的第一個參數只能執行一次
改爲var timer=setInterval(show,600);即可一直循環,間隔0.6s調用