MomentJS : Issue subtracting minutes

Question

This is my code that is deployed on Parse.com CloudCode :

var now = new Date()
var then = moment(now).subtract(20, "minutes").toDate()

console.log(now)
console.log(then)

Why does now === then ?

What am I doing wrong ?

Humes

Answer 1

I don't know you were wrong, but for me works properly. No issues.

>var now = new Date()
>var then = moment(now).subtract(20, "minutes").toDate()
>console.log(now)
>console.log(then)
VM145:5 Thu Jan 21 2016 17:26:48 GMT+0100 (CET)
VM145:6 Thu Jan 21 2016 17:06:48 GMT+0100 (CET)
undefined
>now === then
false

Taradiddle

I've tried again, checked everything, still doesn't work for me :( – Humes

What browser are you using? – Taradiddle

Answer 2

I had the same issue and had to do something similar to this:

const now = new Date()
const nowCopy = new Date()
const then = moment(nowCopy).subtract(20, "minutes").toDate()

console.log(now)
console.log(then)

I know it's not the most elegant solution but it appears your "now" variable is getting mutated when you run an operation on it to get your "then" variable

Tilford

Answer 3

One line answer:

moment(Date.now()).subtract(60, 'minutes').format()

Holmic

Answer 4

I just faced this issue and solved it.

@rishikarri is right, the moment is getting mutated.

All moments are mutable. If you want a clone of a moment, you can do so implicitly or explicitly.

As an alternative to his answer and for future reference, i propose using clone as solution.

There are two ways to clone a moment (According to moment docs):

Using moment():

var a = moment([2012]);
var b = moment(a);
a.year(2000);
b.year(); // 2012

Using .clone():

var a = moment([2012]);
var b = a.clone();
a.year(2000);
b.year(); // 2012

All credit goes to the documentation.

Outmaneuver

Answer 5

If the time is in this format 2022-04-22T15:10:50+05:00 and you want return in the same format then use

moment(startTime).subtract(10, 'minutes').format()

Kilah

Answer 6

try this it work fine with me

let startTime = moment().format('LT');
let subtract = moment(new Date()).subtract(5,"minutes").format('LT');

startTime 12:03 AM

subtract 11:58 PM

Cartercarteret

Answer 7

try using string first then number similiar to this

     let formattedDate = moment(alarmSchedule).subtract('minutes',20).format();
     console.log(formattedDate); // will substract mins from  alarmSchedule time

Worked for me!

Quinones