js ?输出某年某月某日的天数/判断闰年

 ??console.log(getDays(2017,12,12)); ???function getDays(year,month,day){ ???????var arr = [31,28,31,30,31,30,31,31,30,31,30,31]; ???????for(var i=0;i<month-1;i++){ ???????????day += arr[i]; ???????} ???????if(month>2 && isRN(year)){ ???????????day+=1; ???????} ???????return day; ???} ???function isRN(year){ ???????if(year%4===0 && year%100!==0 || year%400===0){ ???????????return true; ???????} ???????return false; ???}