How to add days to a defined Date

Question

I'm trying to set a date like if it was 10 days ago and then I want to create a new date that simply adds 4 days to the first date.

    var date_1 = new Date();
    date_1.setDate(date_1.getDate() - 10);

    var date_2 = date_1;
    date_2.setDate(date_2.getDate() + 4);

The problem is that when I print the variables' dates, they have same value. It seems that date_2 modifies also the date_1.

The output are both: Date 2018-05-28 and I want

date_1 = Date 2018-05-24

date_2 = Date 2018-05-28

Answer 1

Simply create a new Date object using date_1's time. Otherwise you're creating a reference only, that will mutate the original object too

 const date_1 = new Date(); date_1.setDate(date_1.getDate() - 10); const date_2 = new Date(date_1); date_2.setDate(date_2.getDate() + 4); console.log(date_1, date_2)