<!DOCTYPE html><html> ???<head> ???????<meta charset="UTF-8"> ???????<title></title> ???</head> ???<body> ???</body></html><script type="text/javascript"> ???var nian = Number(prompt("请输入年份")); ???var yue = Number(prompt("请输入月份")); ???????if(yue ==1 ||yue ==3 ||yue ==5 ||yue ==7 ||yue ==9||yue ==11 ) ???????{ ???????????alert("31天"); ???????} ???????else if(yue ==2) ???????{ ???????????????????????if ( (nian % 4 == 0) && (nianfen % 100 != 0)) ????????????{ ???????????????alert(nian+"瑞年"+"29天"); ???????????????????????????} ???????????else if(!(nian % 400 == 0)) ???????????{ ???????????????alert(nian+"瑞年"+"29天"); ???????????} ???????????else ???????????{ ???????????????alert(nian+"平年"+"28天"); ???????????} ???????} ???????else{ ???????????alert("30天"); ???????}</script>JS 输入年份，再输入月份，弹出这个月有多少天？
原文地址：https://www.cnblogs.com/hankai2735/p/8776482.html