CODEWITHSUNDEEP
javascriptdate
dartdog
dartdog

Reputation: 10872

Javascript need two date instances Keep getting references instead

How to have a date and subtract 1 year and have a second date for use in display and caculations?

I'm a newbe with JS and find myself fighting the date object
I have declared both currentDate and purchaseDate As var new date() in the globals area But now in a function I try to assign the Original date as "currentDate and the purchaseDate" as one year later,, The alert shows that I have changed the vaue of currentDate rather than just the value of purchaseDate as I intended..

Not what I want! So I get pass by reference vs by value but don't know how to get this so that I have two separate values for the currentDate and the purchaseDate (one year earlier)

currentDate = data.getValue(0,2);
purchaseDate = valueOf(data.getValue(0,2));
purchaseDate.setFullYear(purchaseDate.getFullYear()-1);

alert(purchaseDate);

so this code fails also; That is,, purchase date is 1 year back but so is current date

currentDate = data.getValue(0,2);
    purchaseDate = data.getValue(0,2);
            purchaseDate.setFullYear(purchaseDate.getFullYear()-1);
alert(purchaseDate);

Upvotes: 0

Views: 118

Answers (1)

BalusC
BalusC

Reputation: 1109412

The code which you posted is too ambiguous to reliably point the root cause of your problem (it's unclear what valueOf() is doing), but basically, you indeed need to create a new Date instance based on the time of the other Date. Here's how you could do this, assuming that currentDate is a real Date as well.

var purchaseDate = new Date(currentDate.getTime());

Here's a full kickoff example:

var currentDate = new Date();
var purchaseDate = new Date(currentDate.getTime());
purchaseDate.setFullYear(purchaseDate.getFullYear() - 1);
alert(currentDate); // Today.
alert(purchaseDate); // Today minus one year.

Upvotes: 1

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