js学习笔记9----时间操作
1.时间操作函数如下:
new Date(); //获取系统时间
getFullYear(); //年
getMonth()+1; //月,初始值为0
getDate(); //日
getDay(); //星期,星期日返回的值为0
getHours(); //时
getMinutes(); //分
getSeconds(); //秒
完整示例如下:
<!DOCTYPE html> <html> <head> <title>操作系统时间</title> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <script type="text/javascript"> window.onload = function(){ setInterval(getClock,1000); getClock();//页面打开自动执行,防止刷新1s后才显示 function getClock(){ var oBody = document.body; var str = ""; var myDate = new Date(); //获取系统时间 var iYear = myDate.getFullYear(); //年 var iMonth = myDate.getMonth()+1; //月,初始值为0 var iDate = myDate.getDate(); //日 var iWeek = myDate.getDay(); //星期,星期日返回的值为0 var iHour = myDate.getHours(); //时 var iMin = myDate.getMinutes(); //分 var iSec = myDate.getSeconds(); //秒 if(iWeek === 0) iWeek = "星期日"; if(iWeek === 1) iWeek = "星期一"; if(iWeek === 2) iWeek = "星期二"; if(iWeek === 3) iWeek = "星期三"; if(iWeek === 4) iWeek = "星期四"; if(iWeek === 5) iWeek = "星期五"; if(iWeek === 6) iWeek = "星期六"; str = iYear+"年"+iMonth+"月"+iDate+"日"+ iWeek+ addZero(iHour)+":"+addZero(iMin)+":"+addZero(iSec); oBody.innerHTML = str; } function addZero(n){ //如果当前返回的值小于10,则给它添加一个0 return n<10 ? "0"+n : ""+n; } } </script> </head> <body> </body> </html>
2.倒计时原理:
倒计时在网页中也是一种常见的效果,它的原理就是将两个时间进行比较,然后再把算出来的值进行天,时,分,秒的转化,具体的使用案例如下代码所示:
<!DOCTYPE html> <html> <head> <meta charset="utf-8"> <title>倒计时</title> <script type="text/javascript"> window.onload = function(){ cutdown(); function cutdown(){ var str=""; var timer=null; var iNow = new Date(); //当前日期 var iNew = new Date(2018,4,1,0,0,0); //未来的一个时间,数字形式,月份需要当前月份-1 //var iNew = new Date('August 9,2016 0:0:0'); 字符串形式 var t = Math.floor((iNew - iNow)/1000); //毫秒转化成秒 var day = addZero(Math.floor(t/86400)); //获取天 var hours = addZero(Math.floor(t%86400/3600)); //获取小时 var min = addZero(Math.floor(t%86400%3600/60)); //获取分钟 var sec = addZero(Math.floor(t%60)); //获取秒钟 if(t>=0){ str = "距离2018年国庆节还有:"+day+"天" + hours+"小时"+ min+"分"+ sec+"秒"; document.body.innerHTML = str; }else{ clearInterval(timer); } } function addZero(n){ //如果当前返回的值小于10,则给它添加一个0 return n<10 ? "0"+n : ""+n; } timer = setInterval(cutdown,1000); } </script> </head> <body> </body> </html>