js中的setTimeout实例

//简单的setTimeout的一个时钟function showTime(){    var today = new Date();    var h = today.getHours(),          m =today.getMinutes(),          s = today.getSeconds();    //追加0的判断    m = checkZero(m);    s =  checkZero(s);    //绑给一个id为text的显示    document.getElementById('text').innerHTML = h+":"+m+":"s;    t = setTimeout('showTime()',500);}//内部调用//不做参数类型防范性过滤function checkZero(param){    if(param < 10){       param = "0"+param;      }    return param;}