//判断输入是否是有效的日期格式 "YYYY-MM-DD"
function isdate(str){try{var result=str.match(/^(\d{4})(-|\/)(\d{1,2})\2(\d{1,2})$/);if(result==null) return false;var d= new Date(result[1], result[3]-1, result[4]);return (d.getFullYear()==result[1]&&(d.getMonth()+1)==result[3]&&d.getDate()==result[4]);}catch (e){return false;}}
//比较日期大小 // return true if str1 < str2
function dateDiff(str1,str2){if (!isdate(str1)) return false;if (!isdate(str2)) return false;
var date1 = str1.split('-'); var date2 = str2.split('-');