Adding dates to an array through a loop

Question

I am going through a for loop, adding a time onto the current date, and adding the new date into an array. However, when I output the array once the loop is completed, it is filled with 50 instances of the same date. Logging these dates from within the loop however shows them being incremented correctly. Is this something to do with the data being updated after it has already been pushed into the array?

var dates = new Array();
var currentDate = new Date();
for (var i =0; i < 50;i++){
    currentDate.setDate(currentDate.getDate()+2);
    console.log(currentDate);
    dates.push(currentDate);
}
console.log(dates);

Yogendra Singh · Accepted Answer · 2012-11-09 02:58:28Z

4

Move var currentDate = new Date(); inside for loop. Otherwise you are modifying the same object and adding 50 references of it in the array.

In the end you see the the same object printed 50 times with the last updated date value.

edited Nov 9, 2012 at 2:58

answered Nov 9, 2012 at 2:40

Yogendra Singh

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4 Comments

glenn sayers Over a year ago

But wouldn't that then always give a date 2 days after today? Rather than 50 dates all two days apart?

Eli Gassert Over a year ago

and change the +2 to +(2*i)

Yogendra Singh Over a year ago

@glennsayers: What date are you getting? I think you would be getting all 50 object with same date as 100 days after today i.e. Feb 16, 2013.

glenn sayers Over a year ago

Correct, I am. So it it's putting the same object into the array 50 times, so when I update one object,they all get updated? I get it now. Thanks!

RobG · Accepted Answer · 2012-11-09 02:58:29Z

1

You can do as Yogendra suggests, or change:

> dates.push(currentDate);

to

dates.push(new Date(currentDate));

to get a different date object for each member of the array.

answered Nov 9, 2012 at 2:58

RobG

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