how to change previous date and current date in javascript?

Question

I have an application where I have to display records between two dates, current date and previous date. By default 6 months data are displayed(which is a part of my requirement) but I want to change my previous date during run time(I am passing it from UI) and I don't want to pick future date as current date. Below is my code, please help me to solve this, thank you

// ------------------- function to change dates --------------------- 
    function changeDates(){        
            var date = new Date();
            var cur_date = new Date(date.getFullYear(), date.getMonth() + 1, 0);
            cur_date = cur_date.toString("yyyy-MM-dd");
            cur_date = cur_date.trim();
            var pre_date = new Date(date.getFullYear(), date.getMonth() - 5, 1);
            pre_date = pre_date.toString("yyyy-MM-dd");
            pre_date = pre_date.trim();
            var xmlhttp;
            xmlhttp.open("GET","dashboard/Ajax/change_date.jsp?pre_date="+pre_date+"&cur_date="+cur_date,true);
        xmlhttp.send();

}

Answer 1

From what I can see there are two questions here: 1) Your current date is being created as a future date and 2) You want to be able to override the default pre_date value.

First, when you are calling the Date constructor you are adding a month. This is not necessary. I would read through the MDN on Date .

var cur_date = new Date(date.getFullYear(), date.getMonth(), 1).toString();

Second, the function makes no attempt to change the value of pre_date to override the default. Have the function accept the override date

function changeDates(previousDate)

Then override if a date was passed (you may want to validate the date further):

     var pre_date = previousDate ? 
         previousDate : 
         new Date(date.getFullYear(), date.getMonth() - 5, 1).toString();

Also, I would add that the toString() method does not take any arguments and there should be no need to trim the result.