Javascript how to compare mongoose Date with a String

Question

so I ran into this little problem and I don't know how to solve it. I have two dates, one that comes from a Python script that arrives as a String, and one that comes from a MongoDB object. I need to compare them but the date coming from MongoDB seems to have a strange format that doesn't allow me to do so. This is an example of the dates formats:

String: 29/12/22 15:00
Object: Wed Dec 28 2022 15:00:00 GMT+0100 (hora estándar de Europa central)

From this I can easily transform the String coming from Python to a Date object, but what should I do with the MongoDB object to be able to compare them?

Are you sure? When you say "comes from a MongoDB object" then it seems to be already a Date object and you don't need to convert it. "Wed Dec 28 2022 15:00:00 GMT+0100 (hora estándar de Europa central)" is just the way how your terminal displays it. — Wernfried Domscheit
– Wernfried Domscheit, Commented Jan 2, 2023 at 11:52
Hi @Wernfried Domscheit. I don't understand why, but despite being this data saved as a Date in the model, executing console.log(typeof date2) results on Object — David Jimenez
– David Jimenez, Commented Jan 3, 2023 at 8:25
Then it is a date. typeof new Date() also returns Object — Wernfried Domscheit
– Wernfried Domscheit, Commented Jan 3, 2023 at 8:32
Oh, Okay. Didn't know, thanks for the explanation! I solved it using moments as explained below — David Jimenez
– David Jimenez, Commented Jan 3, 2023 at 8:53

Wernfried Domscheit · Accepted Answer · 2023-01-03 08:55:56Z

1

Based on the information the value from MongoDB (here: date2) is not a string, it is a Date object. Thus you need to convert only the value from Python (here: date1):

if ( moment(date1, 'DD/MM/YY HH:mm').toDate() > date2 ) {
   console.log('true')
} else {
   console.log('false')
}

Or, if you prefer to work with Moment objects:

moment(date1, 'DD/MM/YY HH:mm').isAfter(moment(date2))

answered Jan 3, 2023 at 8:55

Wernfried Domscheit

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1 Comment

David Jimenez Over a year ago

Thanks for taking the time to explain it!

divyesh makvana · Accepted Answer · 2023-01-02 09:07:34Z

1

You can use momentjs to format dates in javascript. He is an Example:

let date1 = "25/12/22 15:00"
let date2 = "Wed Dec 27 2022 15:00:00 GMT+0100"

if(moment(date1,'DD/MM/YY HH:mm') > new Date(date2)){
  console.log('True')
} else {
    console.log('false')
}

<script type = "text/JavaScript" src = " https://MomentJS.com/downloads/moment.js"></script>

answered Jan 2, 2023 at 9:07

divyesh makvana

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4 Comments

Sammed Over a year ago

it is not showing true value for date1 = 27/12/22

Wernfried Domscheit Over a year ago

I think for moment.js you should better use isAfter/isBefore

David Jimenez Over a year ago

@Sammed In case date1 = 27/12/22 as it is same date as date2 I guess you should use the operator >= instead of > at if condition if you want a True in this situation

Sammed Over a year ago

still not working for me

DeeGee · Accepted Answer · 2023-01-02 09:32:34Z

1

Here's a very longhand method: pass the mongo date as a string, split it into its components, and rebuild it. Here, it's rebuilt to the same format as your Python script produces.

function convert(mongoDateString) {
          const monthAr = ["", "Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul", "Aug", "Sep", "Oct", "Nov", "Dec"];
          const mongoDateAr = mongoDateString.split(" ");
          const dayNo = mongoDateAr[2];
          const monthNo = monthAr.indexOf(mongoDateAr[1]);
          const yearNo = mongoDateAr[3];
          const time = mongoDateAr[4].substring(0, mongoDateAr[4].length - 3);
          return dayNo + "/" + monthNo + "/" + yearNo + " " + time;
        }

        let thisDateString = "Wed Dec 28 2022 15:00:00 GMT+0100 (hora estándar de Europa central)"
        console.log(convert(thisDateString ))

edited Jan 2, 2023 at 9:32

answered Jan 2, 2023 at 9:24

DeeGee

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3 Comments

Wernfried Domscheit Over a year ago

Why do you reinvent the wheel? There are many ready-to-use libraries (e.g. Moment.js, Luxon, Day.js) which do this in a single line.

David Jimenez Over a year ago

Hi, thanks for the answer! Seems like doing it with moments it's pretty easier, take a look at the answer if you can. Anyways, thanks for taking your time searching for a solution

DeeGee Over a year ago

Sure there are many libraries, with varying overhead, but I thought the original poster might like to see how date (and other) strings can be manipulated with splitting, as this was something he appeared not to be aware of. When I started, I found this more educative than plugging in a library. But I understand your point.

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