text值改变触发事件跟通过日期获取星期

text值改变触发事件和通过日期获取星期
onpropertychange，只要当前对象属性发生改变，都会触发事件


var mydate=new Date();
var myweekday=mydate.getDay();
var weekday = "";
if(myweekday == 0){
  weekday="星期日";
}else if(myweekday == 1){
  weekday="星期一";
}else if(myweekday == 2){
  weekday="星期二";
}else if(myweekday == 3){
  weekday="星期三";
}else if(myweekday == 4){
  weekday="星期四";
}else if(myweekday == 5){
  weekday="星期五";
}else if(myweekday == 6){
  weekday="星期六";
}