JavaScript实现实时更新系统时间的实例代码

 function getTime(){     str = "当前系统时间："     var p = document.getElementById("sy_time");     time = new Date();     year = time.getFullYear();     month = time.getMonth() + 1;     day = time.getDate();     hour = time.getHours();     minutes = time.getMinutes();     seconds = time.getSeconds();     str = str + year +"-"+ month +"-"+ day + " " +hour+":"+minutes+":"+seconds;     p.innerText = str;     setTimeout(getTime,1000);   }   window.onload = function(){     getTime();   } 

<!-- 页面调用代码 --><p id = "sy_time"></p>