用于检查数据格式的Javascript无法正常工作

我正在尝试编写一个验证，以使用javascript检查日期格式。但我仍然收到错误消息，即使我输入了正确的日期格式，日期格式也无效我不知道我的正则表达式是否正确我在网络上找到了它

感谢您的帮助

function CheckDateFormat()
{
    var StartDateform= document.getElementById('tblTarget').rows[1].cells[StartDate].getElementsByTagName('input')[0].value;
    var pattern;
    // Regular expression used to check if date is in correct format
    pattern= new RegExp("^([0-9]{2})-([0-9]{2})-([0-9]{4})$");
    if(StartDateform.match(pattern))
    {
        var date_array;
        var day;
        date_array = StartDateform.value.split('-');
        day = date_array[0];
        // Attention! Javascript consider months in the range 0 - 11
        var month; 
        var year; 
        month= date_array[1] - 1;
        year= date_array[2];
        // This instruction will create a date object
        //source_date = new Date(year,month,day);
        source_date = new Date(day,month,year);
        if(year != source_date.getFullYear())
        {
            alert('Year is not valid!');
            return false;
        }
        if(month != source_date.getMonth())
        {
            alert('Month is not valid!');
            return false;
        }
        if(day != source_date.getDate())
        {
            alert('Day is not valid!');
            return false;
        }
    }
    else
    {
        alert('Date format is not valid!');
        InvalidFlag=1;
        return false;
    }
    return true;
}