(转)获取月份的天数—javascript实现

//一个月里的天数
function m_DaysInMonth(pYear,pMonth){
    var nDays = 30;
    if(pMonth==2){    //2月单独处理
        if(mIsLeap(pYear)) nDays = 29;
        else nDays = 28;
    }
    else if(mInList(pMonth,"1,3,5,7,8,10,12")){
        nDays = 31;   
    }
    return nDays;
}

//判断某年是否是闰年
function m_IsLeap(pYear){
    if(pYear % 400 == 0){
        return true;
    }
    else if((pYear % 100 != 0) && (pYear % 4 == 0)){
        return true;
    }
    return false;
}

//判断是否在字符串列表里：
// if(mInList("3","1,3,5,7,8,10,12")){   //true
// if(mInList("2","1,3,5,7,8,10,12")){   //false

function mInList(s1,slist){
   var ss1=","+s1+",";
   var ss2=","+slist+",";
   ss1 = ss1.toLowerCase();
   ss2 = ss2.toLowerCase();
   return ss2.indexOf(ss1)!=-1;
}

转自：http://weichaozu.blog.163.com/blog/static/123192959200962853711/