一个计算“整星期日期”的小功能

时间：2010-08-24 来源：大虾米
代码
<html>
<head>
    <title>日期插件</title>
</head>
<body>
    <script type="text/javascript">
        function myDate() {
            function formatDate(d) {
                var _todayDate = d.getDate();
                var _year = d.getYear();
                !document.addEventListener || (_year += 1900);
                var _month = d.getMonth()+1;
                return _year+"-"+_month+"-"+_todayDate;
            }
            var now = new Date(), dd = new Date();
            var n = now.getDay();
            function check(date,m) {
                for (var i = 0;i < 7; i++) {
                    var datevalue = now.getDate()-n+m+i+1;
                    var month = now.getMonth()+1;
                    if (month == 1 || month == 3 || month == 5 || month == 7 || month == 8 || month == 10 || month == 12) {
                        if (datevalue > 31) {
                            if ( m < 0 && month - 1 != 2) {
                                dd.setDate(31-(30-datevalue));
                                dd.setMonth(month)
                            }
                            else
                            {
                                dd.setDate(datevalue - 31);
                                dd.setMonth(month);
                            }        
                        }
                        else
                        {
                            dd.setDate(datevalue);
                        }
                    }
                    else if (month == 4 || month == 6 || month == 9 || month == 11) 
                    {
                        if (datevalue > 30) {
                            if ( m < 0 && month - 1 != 2) {
                                dd.setDate(31-(30-datevalue));
                                dd.setMonth(month)
                            }
                            else
                            {
                                dd.setDate(datevalue - 30);
                                dd.setMonth(month);
                            }
                        }
                        else
                        {
                            dd.setDate(datevalue);
                        }
                        }
                    else if (month == 2) {
                        if (datevalue > 28) {
                            dd.setDate(datevalue - 28);
                            m >= 0 ? dd.setMonth(month+1) : dd.setMonth(month-1);
                        }
                        else
                        {
                            dd.setDate(datevalue);
                        }
                    }
                    date.push(formatDate(dd));
                }
                
            }
            
            return {
                currWeek : function () {
                    var date = [];
                    check(date, 0);
                    return date;
                },
                nextWeek : function () {
                    var date = [];
                    check(date, 7);
                    return date;
                },
                prevWeek : function () {
                    var date = [];
                    check(date, -7);
                    return date;
                }
            }
        }
        var s = new myDate();
        document.write("上星期的每天日期："+s.prevWeek()+"<br />"+"本星期的每天日期；"+s.currWeek()+"<br />"+"下星期的每天日期："+s.nextWeek());
    </script>
</body>
</html>