CODEWITHSUNDEEP
javascriptdate
user4235401
user4235401

Reputation:

getMonth() minus something is giving weird results

I have a code in which I am testing the difference in months between two dates. To get old date I am doing following thing

  var oldDate = new Date();
  oldDate.setMonth(oldDate.getMonth() - 5);

But monthsOldDate is returning something else and not five month old date why is this behaving weirdly today? and how shall I fix this?

Upvotes: 1

Views: 703

Answers (2)

supra28
supra28

Reputation: 1636

When trying to add or subtract months from a Javascript Date() Object which is an end date of a month, JS automatically advances your Date object to next month’s first date if the resulting date does not exist in its month.

I would recommend using a library like momentjs for this

You can do this by 

var monthsOldDate = moment().subtract(6, 'months');

console.log(monthsOldDate.month()) //will log 10 (November)
monthsOldDate = monthsOldDate.set("month", monthsOldDate.month())
console.log(monthsOldDate.format("Do MMMM YYYY"))  //30th November 2017

Upvotes: 1

chuckx
chuckx

Reputation: 6877

It's because it's the 31st.

When you call the setMonth() method with the argument -2, it sets the date to 31 Nov 2017. That's not an actual date, so it gets converted to 1 Dec 2017.

See the last paragraph of the Description section for an explanation of this behavior.

Upvotes: 3

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