Question

I have a string which has a date in the format: dd-mm-yyyy

How I can add 4 weeks to the string and then generate a new string using jQuery / Javascript?

I have

var d = new Date(current_date); 
d.setMonth(d.getMonth() + 1); 
current_date_new = (d.getMonth() + 1 ) + '-' + d.getDate() + '-' + d.getFullYear();    
alert(current_date_new); 

but it complains that the string provided is in the incorrect format

Answer 1

EDIT: After a bit of fiddling, here’s the solution:

First, split the string to individual parts.

var inputString = "12-2-2005";
var dString = inputString.split('-');

Then, parse the string to a datetime object and add 28 days (4 weeks) to it.

var dt = new Date(dString[2],dString[1]-1,dString[0]);
dt.setDate(dt.getDate()+28);

Finally, you can output the date

var finalDate = dt.GetDate() + "-" + (dt.GetMonth()+1) + "-" + dt.GetYear();

This code should return 12-3-2005.

CAVEATS: It seems JavaScript’s Date object takes 0-11 as the month field, hence the -1 and +1 to the month in the code.

EDIT2: To do padding, use this function:

function pad(number, length) {

    var str = '' + number;
    while (str.length < length) {
        str = '0' + str;
    }

    return str;

}

and change your output to

var finalDate = pad(dt.GetDate(),2) + "-" + pad(dt.GetMonth()+1,2) + "-" + dt.GetYear();

Check the updated fiddle.