在javascript中获取一周的前几天和后几天

Question

I have this code that get the current date, then get also the days of the week. Sometimes this code is not working, for example, today is 08/15, I will get 08/13. I need also to have a function get the previous and next days of the week.

var self = this;
var curr = new Date;
self.mult = 0;
    self.firstDate = new Date;
    self.lastDate = new Date;
    var first = curr.getDate() - (curr.getDay()-1);
    var last = first + 6; 
    self.firstDate(Utils.dateFormat(new Date(curr.setDate(first)),"%Y-%m-%d", true));
    self.lastDate(Utils.dateFormat(new Date(curr.setDate(last)),"%Y-%m-%d", true));

And this is the function to see previous days of the week,

var self= this;
    var curr = new Date;
    self.mult(self.mult()-7);
    var first = curr.getDate() - (curr.getDay()-1) + self.mult();
    var last = first + 5;
    if(self.mult() <= 0){
        last = last + 1;
    }
    self.firstDate(Utils.dateFormat(new Date(curr.setDate(first)),"%Y-%m-%d", true));
    self.lastDate(Utils.dateFormat(new Date(curr.setDate(last)),"%Y-%m-%d", true));

And this is the function to see the next days of the week,

var self= this;
    var curr = new Date;
    self.mult(self.mult()+7);
    var first = curr.getDate() - (curr.getDay()-1) + self.mult();
    var last = first + 5;
    self.firstDate(Utils.dateFormat(new Date(curr.setDate(first)),"%Y-%m-%d", true));
    self.lastDate(Utils.dateFormat(new Date(curr.setDate(last)),"%Y-%m-%d", true));

I am not sure but I think only previous days of the week is the problem.

Here is a sample situation.

Scenario 1: User visit a page, the today is 09/15 then the firstDate must be 09/12 then lastDate must be 09/18 the user click next, then the firstDate must be 09/19 and the lastDate is 09/25 the user click next again, then the firstDate is 09/26 and the lastDate is 10/02 the user click previous, then the firstDate must be 09/19 and the lastDate is 09/25

Scenario 2: User visit a page, the today is 09/15 then the firstDate must be 09/12 then lastDate must be 09/18 the user click previous, then the firstDate must be 09/5 and the lastDate is 09/11 the user click previous again, then the firstDate must be 08/29 and the lastDate is 09/4 the user click next, then the firstDate must be 09/5 and the lastDate is 09/11

Can someone answer a code that can do my scenarios?

Answer 1

You can use setDate()

for example:

var a = new Date();
console.log(a)
//Thu Sep 15 2016 10:22:25 GMT+0200 (CEST)
a.setDate(a.getDate()+1);
console.log(a)
//Fri Sep 16 2016 10:22:25 GMT+0200 (CEST)

Answer 2

I'd recommend use library for tasks like this. For example moment.js.

Start of week from now

moment(new Date()).startOf('isoWeek').format('MMMM Do YYYY, h:mm:ss ')

End of week from now

moment(new Date()).endOf('isoWeek').format('MMMM Do YYYY, h:mm:ss ')

For more details please see: http://momentjs.com/