js implements calendar to obtain the specified date, week number and day of the week. Example sharing

Because there is interaction, I chose Js to implement it, which can be regarded as the first try of pair programming. I wrote the display part in HTML. The clicked button trigger event function is check();

function onCheck(){ 
var Year = document.getElementById("year").value; //获取文本框的“年” var theYear =Year * 1; //转换为number类型 //alert(theYear); // 获取月值 
var month = document.getElementById("month"); 
var index1=month.selectedIndex; var theMonth = month.options[index1].value; //获取月值 
var day = document.getElementById("day"); 
var index2=day.selectedIndex; 
var theDay = day.options[index2].value;
// 输入值判断部分
...
//调用核心函数
days(theYear,theMonth,theDay); 
}

The core function days are as follows:

function days(year,month,day) { 
    var days = 0;  //表示改日期为当年的第几天
    //累加月天数
    for(var i = 1; i < month; i++ ){
    switch(i){
    //大月的情况加31
    case 1:
    case 3:
    case 5:
    case 7:
    case 8:
    case 10:
    case 12:{
    days += 31;
    break;
    }
    //小月的情况加30
    case 4:
    case 6:
    case 9:
    case 11:{
    days += 30;
    break;
    }
    //二月的情况，根据年类型来加
    case 2:{
        if(isLeapYear(year)){
        days += 29; //闰年加29
        }
        else {
        days += 28;
        }
    break;
    }
    }
}
day = day * 1;
days += day;  //月天数之和加上日天数
var date0 = new Date(year,0,1);   //当年的第一天是周几
//   alert(date0.getDay());
    var date1 = new Date(year,month-1,day); //将日期值格式化,0-11代表1月-12月；
//   alert((days + date0.getDay()+6)/7);
    var nthOfWeek = Math.floor((days + date0.getDay()+6)/7);  //向下取整
//   alert(nthOfWeek);
    var toDay = new Array("星期天","星期一","星期二","星期三","星期四","星期五","星期六"); 
    //day.getDay();根据Date返一个星期中的某其中0为星期日 
    alert("该日期是一年中的第"+days+"天\n"+"     是第"+nthOfWeek+"周的"+toDay[date1.getDay()]);
}

I encountered many unexpected errors during the debugging process, such as Calculation errors caused by type mismatch, such as number rounding problems;
With the assistance of teammates, he is responsible for reviewing and assisting in catching bugs, and I am responsible for implementation and coding;
In the last link, the input During the value testing, we assisted each other very well, analyzed different input situations, covered various possible accidents, and quickly completed the function improvement;
The following is the code to determine whether the input value is allowed:

if (isNaN(theYear)|| theYear < 0) {
  alert("输入有误，请重新输入");
  return ;
}
if((theMonth == 2 && theDay > 29 && isLeapYear(theYear))||(theMonth == 2 && theDay > 28 && !isLeapYear(theYear))) {
  alert("输入有误，请重新输入");
  return ;
}
if((theMonth == 4 || theMonth == 6 || theMonth == 9 || theMonth == 11) && theDay == 31 ) {
  alert("输入有误，请重新输入");
  return ;
}

For more js implementation of the calendar, you can get the specified date, week number and day of the week. For related articles, please pay attention to the PHP Chinese website!