<!doctype html> <html> <head> <meta charset="utf-8"> <title>计算当前月有几天</title> <script> var oDate=new Date(); oDate.setMonth(oDate.getMonth()+1, 1); // 11-1下个月的月初 oDate.setDate(0); // 10-31 上个月底 alert((oDate.getMonth()+1)+'-'+oDate.getDate()); </script> </head> <body> </body> </html>